[ { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/97csb-6dg75", "eprint_status": "archive", "datestamp": "2024-02-01 17:51:27", "lastmod": "2024-02-05 19:44:31", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhong-Ding", "name": { "family": "Zhong", "given": "Ding" }, "orcid": "0000-0003-3149-2071" }, { "id": "Gao-Shiyuan", "name": { "family": "Gao", "given": "Shiyuan" }, "orcid": "0000-0002-9069-5306" }, { "id": "Saccone-Max", "name": { "family": "Saccone", "given": "Max" }, "orcid": "0000-0003-3846-2908" }, { "id": "Greer-J-R", "name": { "family": "Greer", "given": "Julia R." }, "orcid": "0000-0002-9675-1508" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Nadj-Perge-S", "name": { "family": "Nadj-Perge", "given": "Stevan" }, "orcid": "0000-0002-2394-9070" }, { "id": "Faraon-A", "name": { "family": "Faraon", "given": "Andrei" }, "orcid": "0000-0002-8141-391X" } ] }, "title": "Carbon-Related Quantum Emitter in Hexagonal Boron Nitride with Homogeneous Energy and 3-Fold Polarization", "ispublished": "pub", "full_text_status": "public", "keywords": "Mechanical Engineering; Condensed Matter Physics; General Materials Science; General Chemistry; Bioengineering", "note": "
© 2024 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY 4.0.
\n\nThis work was supported by the U.S. Department of Energy under Grant DE-SC0019166. A.F. and M.B. acknowledge the support from the National Science Foundation under Grant 1936350. The authors thank Riku Fukumori and Brian Doherty for their help.
\nThe authors declare no competing financial interest.
", "abstract": "Most hexagonal boron nitride (hBN) single-photon emitters (SPEs) studied to date suffer from variable emission energy and unpredictable polarization, two crucial obstacles to their application in quantum technologies. Here, we report an SPE in hBN with an energy of 2.2444 ± 0.0013 eV created via carbon implantation that exhibits a small inhomogeneity of the emission energy. Polarization-resolved measurements reveal aligned absorption and emission dipole orientations with a 3-fold distribution, which follows the crystal symmetry. Photoluminescence excitation (PLE) spectroscopy results show the predictability of polarization is associated with a reproducible PLE band, in contrast with the non-reproducible bands found in previous hBN SPE species. Photon correlation measurements are consistent with a three-level model with weak coupling to a shelving state. Our ab initio excited-state calculations shed light on the atomic origin of this SPE defect, which consists of a pair of substitutional carbon atoms located at boron and nitrogen sites separated by a hexagonal unit cell.
\n\u00a9 2023 American Chemical Society.
\n\nThe author acknowledges fruitful discussions with Sijing Du, Sandeep Sharma, and Garnet Chan. This work was supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, and Office of Basic Energy Sciences, Scientific Discovery through Advanced Computing (SciDAC) program under award number DE-SC0022088.
\n\nThe data sets generated and analyzed in this study, as well as the QC-DFT codes, will be made available in the CaltechDATA repository. Additional data and information are available upon reasonable request. The QuEST code (6) used for the exact QC simulations is an open source software, which can be downloaded at https://quest.qtechtheory.org. The QC drawings were prepared using the Quantikz LaTeX package, (36) which can be downloaded at https://ctan.org/pkg/quantikz. The QC-DFT Python code will be made available in the CaltechDATA repository.
\n\nThe author declares no competing financial interest.
", "abstract": "Exact simulations of quantum circuits (QCs) are currently limited to \u223c50 qubits because the memory and computational cost required to store the QC wave function scale exponentially with qubit number. Therefore, developing efficient schemes for approximate QC simulations is a current research focus. Here, we show simulations of QCs with a method inspired by density functional theory (DFT), a widely used approach for studying many-electron systems. Our calculations can predict marginal single-qubit probabilities (SQPs) with over 90% accuracy in several classes of QCs with universal gate sets, using memory and computational resources linear in qubit number despite the formal exponential cost of the SQPs. This is achieved by developing a mean-field description of QCs and formulating optimal single- and two-qubit gate functionals\u2500analogues of exchange-correlation functionals in DFT\u2500to evolve the SQPs without computing the QC wave function. Current limitations and future extensions of this formalism are discussed.
", "date": "2023-11-28", "date_type": "published", "publication": "Journal of Chemical Theory and Computation", "volume": "19", "number": "22", "publisher": "American Chemical Society", "pagerange": "8066-8075", "issn": "1549-9618", "official_url": "https://authors.library.caltech.edu/records/hv60e-7ra63", "funders": { "items": [ { "grant_number": "DE-SC0022088" } ] }, "doi": "10.1021/acs.jctc.3c00607", "primary_object": { "basename": "ct3c00607_si_001.pdf", "url": "https://authors.library.caltech.edu/records/hv60e-7ra63/files/ct3c00607_si_001.pdf" }, "resource_type": "article", "pub_year": "2023", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kac6j-91v06", "eprint_status": "archive", "datestamp": "2023-10-16 20:33:27", "lastmod": "2023-10-16 20:33:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Abramovitch-David-J", "name": { "family": "Abramovitch", "given": "David J." } }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Mravlje-Jernej", "name": { "family": "Mravlje", "given": "Jernej" }, "orcid": "0000-0001-6174-2401" }, { "id": "Georges-Antoine", "name": { "family": "Georges", "given": "Antoine" }, "orcid": "0000-0001-9479-9682" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Combining electron-phonon and dynamical mean-field theory calculations of correlated materials: Transport in the correlated metal Sr\u2082RuO\u2084", "ispublished": "pub", "full_text_status": "public", "keywords": "Physics and Astronomy (miscellaneous); General Materials Science", "note": "\u00a9 2023 American Physical Society.
\n\nThe authors thank M. Zingl for sharing DMFT data and for fruitful discussions. J.M. acknowledges useful correspondence with F. Baumberger. This work was primarily supported by the National Science Foundation under Grant No. DMR-1750613, which provided for method development, and Grant No. OAC-2209262, which provided for code development. D.J.A. and M.B. were partially supported by the AFOSR and Clarkson Aerospace under Grant No. FA95502110460. J.-J.Z. acknowledges support from the National Natural Science Foundation of China (Grant No. 12104039). J.M. is supported by the Slovenian Research Agency (ARRS) under Grants No. P1-0044 and No. J1-2458. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231 using NERSC award BES-ERCAP-0023043.
", "abstract": "Electron-electron (e\u2212e) and electron-phonon (e-ph) interactions are challenging to describe in correlated materials, where their joint effects govern unconventional transport, phase transitions, and superconductivity. Here we combine first-principles e-ph calculations with dynamical mean-field theory (DMFT) as a step toward a unified description of e\u2212e and e-ph interactions in correlated materials. We compute the e-ph self-energy using the DMFT electron Green's function and combine it with the e\u2212e self-energy from DMFT to obtain a Green's function including both interactions. This approach captures the renormalization of quasiparticle dispersion and spectral weight on equal footing. Using our method, we study the e-ph and e\u2212e contributions to the resistivity and spectral functions in the correlated metal Sr\u2082RuO\u2084. In this material, our results show that e\u2212e interactions dominate transport and spectral broadening in the temperature range we study (50\u2013310 K), while e-ph interactions are relatively weak and account for only \u223c10% of the experimental resistivity. We also compute effective scattering rates and find that the e\u2212e interactions result in scattering several times greater than the Planckian value kBT, whereas e-ph interactions are associated with scattering rates lower than kBT. Our work demonstrates a first-principles approach to combine electron dynamical correlations from DMFT with e-ph interactions in a consistent way, advancing quantitative studies of correlated materials.
", "date": "2023-09", "date_type": "published", "publication": "Physical Review Materials", "volume": "7", "number": "9", "publisher": "American Physical Society", "pagerange": "093801", "issn": "2475-9953", "official_url": "https://authors.library.caltech.edu/records/kac6j-91v06", "funders": { "items": [ { "grant_number": "DMR-1750613" }, { "grant_number": "OAC-2209262" }, { "grant_number": "FA95502110460" }, { "grant_number": "12104039" }, { "grant_number": "P1-0044" }, { "grant_number": "J1-2458" }, { "grant_number": "BES-ERCAP-0023043" }, { "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/physrevmaterials.7.093801", "primary_object": { "basename": "PhysRevMaterials.7.093801.pdf", "url": "https://authors.library.caltech.edu/records/kac6j-91v06/files/PhysRevMaterials.7.093801.pdf" }, "related_objects": [ { "basename": "Sr2RuO4_Paper_SI-4.pdf", "url": "https://authors.library.caltech.edu/records/kac6j-91v06/files/Sr2RuO4_Paper_SI-4.pdf" } ], "resource_type": "article", "pub_year": "2023", "author_list": "Abramovitch, David J.; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/942mw-k5z34", "eprint_id": 122035, "eprint_status": "archive", "datestamp": "2023-08-20 16:45:28", "lastmod": "2023-10-20 16:55:59", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Desai-Dhruv-C", "name": { "family": "Desai", "given": "Dhruv C." } }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Dominant two-dimensional electron-phonon interactions in the bulk Dirac semimetal Na\u2083Bi", "ispublished": "unpub", "full_text_status": "public", "note": "D.D. and J.P. thank Ivan Maliyov for fruitful discussions. This work was supported by the National Science Foundation under Grant No. DMR-1750613, which provided for method development, and Grant No. OAC-2209262, which provided for code development. M. B. was partially supported by the AFOSR and Clarkson Aerospace under Grant No. FA95502110460. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nSubmitted - 2303.17068.pdf
", "abstract": "Bulk Dirac semimetals (DSMs) exhibit unconventional transport properties and phase transitions due to their peculiar low-energy band structure. Yet the electronic interactions governing nonequilibrium phenomena in DSMs are not fully understood. Here we show that electron-phonon (e-ph) interactions in a prototypical bulk DSM, Na3Bi, are predominantly two-dimensional (2D). Our first-principles calculations discover a 2D optical phonon with strong e-ph interactions associated with in-plane vibrations of Na atoms. We show that this 2D mode governs e-ph scattering and charge transport in Na\u2083Bi, and induces a dynamical phase transition to a Weyl semimetal. Our work advances quantitative analysis of electron interactions in topological semimetals and reveals dominant low-dimensional interactions in bulk quantum materials.", "date": "2023-06-28", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20230628-175652000.1", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230628-175652000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "OAC-2209262" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA95502110460" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "primary_object": { "basename": "2303.17068.pdf", "url": "https://authors.library.caltech.edu/records/942mw-k5z34/files/2303.17068.pdf" }, "resource_type": "monograph", "pub_year": "2023", "author_list": "Desai, Dhruv C.; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/e8gxh-4j988", "eprint_id": 122088, "eprint_status": "archive", "datestamp": "2023-08-22 21:03:59", "lastmod": "2023-10-20 16:57:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Computing electron dynamics in momentum space", "ispublished": "pub", "full_text_status": "public", "keywords": "Computer Networks and Communications; Computer Science Applications; Computer Science (miscellaneous)", "note": "The author declares no competing interests.", "abstract": "A momentum-space algorithm is proposed to simulate electron dynamics with time-dependent density functional theory, which expands the scope of conventional real-space methods.", "date": "2023-06", "date_type": "published", "publication": "Nature Computational Science", "volume": "3", "number": "6", "publisher": "Nature Publishing Group", "pagerange": "480-481", "id_number": "CaltechAUTHORS:20230630-22193000.3", "issn": "2662-8457", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230630-22193000.3", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1038/s43588-023-00473-8", "resource_type": "article", "pub_year": "2023", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7yp8q-83f64", "eprint_id": 121413, "eprint_status": "archive", "datestamp": "2023-08-22 20:54:22", "lastmod": "2023-10-20 15:27:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Desai-Dhruv-C", "name": { "family": "Desai", "given": "Dhruv C." } }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Dominant Two-Dimensional Electron-Phonon Interactions in the Bulk Dirac Semimetal Na\u2083Bi", "ispublished": "pub", "full_text_status": "public", "keywords": "Mechanical Engineering; Condensed Matter Physics; General Materials Science; General Chemistry; Bioengineering", "note": "\u00a9 2023 American Chemical Society. \n\nD.C.D. and J.P. thank Ivan Maliyov for fruitful discussions. This work was supported by the National Science Foundation under Grant DMR-1750613, which provided for method development, and Grant OAC-2209262, which provided for code development. M.B. was partially supported by the AFOSR and Clarkson Aerospace under Grant FA95502110460. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract DE-AC02-05CH11231. \n\nAuthor Contributions. D.C.D. and J.P. contributed equally to this work. \n\nThe authors declare no competing financial interest.", "abstract": "Bulk Dirac semimetals (DSMs) exhibit unconventional transport properties and phase transitions due to their peculiar low-energy band structure, yet the electronic interactions governing nonequilibrium phenomena in DSMs are not fully understood. Here we show that electron\u2013phonon (e\u2013ph) interactions in a prototypical bulk DSM, Na3Bi, are predominantly two-dimensional (2D). Our first-principles calculations reveal a 2D optical phonon with strong e\u2013ph interactions associated with in-plane vibrations of Na atoms. We show that this 2D mode governs e\u2013ph scattering and charge transport in Na\u2083Bi and induces a dynamical phase transition to a Weyl semimetal. Our work advances the quantitative analysis of electron interactions in Na\u2083Bi and reveals a dominant low-dimensional interaction in a bulk Dirac semimetal.", "date": "2023-05-10", "date_type": "published", "publication": "Nano Letters", "volume": "23", "number": "9", "publisher": "American Chemical Society", "pagerange": "3947-3953", "id_number": "CaltechAUTHORS:20230516-592783300.5", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230516-592783300.5", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "OAC-2209262" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA95502110460" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1021/acs.nanolett.3c00713", "resource_type": "article", "pub_year": "2023", "author_list": "Desai, Dhruv C.; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kkdea-vwz09", "eprint_id": 121513, "eprint_status": "archive", "datestamp": "2023-08-22 20:54:33", "lastmod": "2023-10-20 15:30:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Desai-Dhruv-C", "name": { "family": "Desai", "given": "Dhruv C." } }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Dominant Two-Dimensional Electron\u2013Phonon Interactions in the Bulk Dirac Semimetal Na\u2083Bi", "ispublished": "pub", "full_text_status": "public", "keywords": "Mechanical Engineering; Condensed Matter Physics; General Materials Science; General Chemistry; Bioengineering", "note": "\u00a9 2023 American Chemical Society. \n\nD.C.D. and J.P. thank Ivan Maliyov for fruitful discussions. This work was supported by the National Science Foundation under Grant DMR-1750613, which provided for method development, and Grant OAC-2209262, which provided for code development. M.B. was partially supported by the AFOSR and Clarkson Aerospace under Grant FA95502110460. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract DE-AC02-05CH11231. \n\nAuthor Contributions. D.C.D. and J.P. contributed equally to this work. \n\nThe authors declare no competing financial interesst.", "abstract": "Bulk Dirac semimetals (DSMs) exhibit unconventional transport properties and phase transitions due to their peculiar low-energy band structure, yet the electronic interactions governing nonequilibrium phenomena in DSMs are not fully understood. Here we show that electron\u2013phonon (e\u2013ph) interactions in a prototypical bulk DSM, Na3Bi, are predominantly two-dimensional (2D). Our first-principles calculations reveal a 2D optical phonon with strong e\u2013ph interactions associated with in-plane vibrations of Na atoms. We show that this 2D mode governs e\u2013ph scattering and charge transport in Na\u2083Bi and induces a dynamical phase transition to a Weyl semimetal. Our work advances the quantitative analysis of electron interactions in Na3Bi and reveals a dominant low-dimensional interaction in a bulk Dirac semimetal.", "date": "2023-05-10", "date_type": "published", "publication": "Nano Letters", "volume": "23", "number": "9", "publisher": "American Chemical Society", "pagerange": "3947-3953", "id_number": "CaltechAUTHORS:20230524-374122000.16", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230524-374122000.16", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "OAC-2209262" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-21-1-0460" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "Clarkson Aerospace" } ] }, "doi": "10.1021/acs.nanolett.3c00713", "resource_type": "article", "pub_year": "2023", "author_list": "Desai, Dhruv C.; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/tsf34-9n109", "eprint_status": "archive", "datestamp": "2023-10-04 18:50:56", "lastmod": "2023-10-04 18:50:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Desai-Dhruv-C", "name": { "family": "Desai", "given": "Dhruv C." } }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Dominant Two-Dimensional Electron\u2013Phonon Interactions in the Bulk Dirac Semimetal Na\u2083Bi", "ispublished": "pub", "full_text_status": "public", "keywords": "Mechanical Engineering; Condensed Matter Physics; General Materials Science; General Chemistry; Bioengineering", "note": "\u00a9 2023 American Chemical Society.
\n\nD.C.D. and J.P. thank Ivan Maliyov for fruitful discussions. This work was supported by the National Science Foundation under Grant DMR-1750613, which provided for method development, and Grant OAC-2209262, which provided for code development. M.B. was partially supported by the AFOSR and Clarkson Aerospace under Grant FA95502110460. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract DE-AC02-05CH11231.
\n\nD.C.D. and J.P. contributed equally to this work.
\n\nThe authors declare no competing financial interest.
", "abstract": "Bulk Dirac semimetals (DSMs) exhibit unconventional transport properties and phase transitions due to their peculiar low-energy band structure, yet the electronic interactions governing nonequilibrium phenomena in DSMs are not fully understood. Here we show that electron\u2013phonon (e\u2013ph) interactions in a prototypical bulk DSM, Na\u2083Bi, are predominantly two-dimensional (2D). Our first-principles calculations reveal a 2D optical phonon with strong e\u2013ph interactions associated with in-plane vibrations of Na atoms. We show that this 2D mode governs e\u2013ph scattering and charge transport in Na\u2083Bi and induces a dynamical phase transition to a Weyl semimetal. Our work advances the quantitative analysis of electron interactions in Na\u2083Bi and reveals a dominant low-dimensional interaction in a bulk Dirac semimetal.
", "date": "2023-05-10", "date_type": "published", "publication": "Nano Letters", "volume": "23", "number": "9", "publisher": "American Chemical Society", "pagerange": "3947-3953", "issn": "1530-6984", "official_url": "https://authors.library.caltech.edu/records/tsf34-9n109", "funders": { "items": [ { "grant_number": "DMR-1750613" }, { "grant_number": "OAC-2209262" }, { "grant_number": "FA95502110460" }, { "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1021/acs.nanolett.3c00713", "resource_type": "article", "pub_year": "2023", "author_list": "Desai, Dhruv C.; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0hmc6-19g91", "eprint_id": 119073, "eprint_status": "archive", "datestamp": "2023-08-20 08:41:51", "lastmod": "2023-10-24 23:49:21", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Efficient Mean-Field Simulation of Quantum Circuits Inspired by the Many-Electron Problem", "ispublished": "unpub", "full_text_status": "public", "note": "Attribution 4.0 International (CC BY 4.0).\n\nThis work was supported by the National Science Foundation under Grant No. 1750613, which provided for method development. M.B. was also supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research and Office of Basic Energy Sciences, Scientific Discovery through Advanced Computing (SciDAC) program under Award Number DE-SC0022088, which supported code development. \n\nAUTHOR CONTRIBUTIONS. M.B. conceived and designed the research, performed the calculations and analysis, and wrote the manuscript. \n\nDATA AVAILABILITY. The data sets generated and analyzed in this study, as well as the QC-DFT codes, will be made available in the CaltechDATA repository. Additional data and information are available upon reasonable request. \n\nCODE AVAILABILITY. The QuEST code3 used for the exact QC simulations is an open source software, which can be downloaded at https://quest.qtechtheory.org. The QC drawings were preparedusing the Quantikz LaTeX package, which can be downloaded at https://ctan.org/pkg/quantikz. The QC-DFT Python code will be made available in the CaltechDATA repository. \n\nThe authors declare no competing interests.\n\nSubmitted - 2210.16465.pdf
", "abstract": "Classical simulations can provide the exact wave function of quantum circuits (QCs), but are currently limited to \u223c50 qubits due to their memory and computational cost, which scale exponentially with qubit number. As quantum hardware advances toward hundreds of interacting qubits, developing reliable schemes for approximate QC simulations has become a priority. Here we show efficient simulations of QCs with a method inspired by density functional theory (DFT), a widely used approach to study many-electron systems. We demonstrate accurate simulations of various QCs with universal gate sets, reaching up to a billion qubits in size, using only laptop calculations. Our simulations can predict marginal single-qubit probabilities (SQPs) with over 90\\% accuracy, using memory and computational resources linear in qubit number despite the formal exponential cost of SQPs. We achieve these results by adopting a mean-field description of QCs, and formulating optimal single- and two-qubit gate functionals \u2212 analogs of exchange-correlation functionals in DFT \u2212 to evolve the SQPs without computing the QC wave function. Our findings pave the way for accurate simulations of large QCs and provide a blueprint to adapt electronic structure methods to QC simulations.", "date": "2023-02-09", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20230207-190610226", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230207-190610226", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022088" } ] }, "doi": "10.48550/arXiv.2210.16465", "primary_object": { "basename": "2210.16465.pdf", "url": "https://authors.library.caltech.edu/records/0hmc6-19g91/files/2210.16465.pdf" }, "resource_type": "monograph", "pub_year": "2023", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hk4c3-ncy21", "eprint_id": 118849, "eprint_status": "archive", "datestamp": "2023-08-22 18:20:06", "lastmod": "2023-10-23 20:20:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Sangalli-Davide", "name": { "family": "Sangalli", "given": "Davide" }, "orcid": "0000-0002-4268-9454" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "First-principles ultrafast exciton dynamics and time-domain spectroscopies: Dark-exciton mediated valley depolarization in monolayer WSe\u2082", "ispublished": "pub", "full_text_status": "public", "keywords": "General Physics and Astronomy", "note": "Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\nThe authors thank Ivan Maliyov and Jinsoo Park for fruitful discussions. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research and Office of Basic Energy Sciences, Scientific Discovery through Advanced Computing (SciDAC) program under Award No. DESC0022088, which supported method development. M.B. was partially supported by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0021266. Code development was partially funded by the National Science Foundation under Grant No. OAC-2209262. H.-Y. Chen was partially supported by the J. Yang Fellowship. D.S. acknowledges funding from Italian MIUR, PRIN BIOX Grant No. 20173B72NB, and from the EU MaX project Materials design at the eXascale H2020-INFRAEDI-2018-2020, Grant Agreement No. 824143. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevResearch.4.043203.pdf
", "abstract": "Calculations combining first-principles electron-phonon (e-ph) interactions with the Boltzmann equation enable studies of ultrafast carrier and phonon dynamics. However, in materials with weak Coulomb screening, electrons and holes form bound excitons so their scattering processes become correlated, posing additional challenges for modeling nonequilibrium physics. Here we show calculations of ultrafast exciton dynamics and related time-domain spectroscopies using ab initio exciton-phonon (ex-ph) interactions together with an excitonic Boltzmann equation. Starting from the nonequilibrium exciton populations, we develop simulations of time-domain absorption and photoemission spectra that take into account electron-hole correlations. We use this method to study monolayer WSe\u2082, where our calculations predict subpicosecond timescales for exciton relaxation and valley depolarization and reveal the key role of intermediate dark excitons. The approach introduced in this paper enables a quantitative description of nonequilibrium dynamics and ultrafast spectroscopies in materials with strongly bound excitons.", "date": "2022-12", "date_type": "published", "publication": "Physical Review Research", "volume": "4", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. 043203", "id_number": "CaltechAUTHORS:20230118-50417000.1", "issn": "2643-1564", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230118-50417000.1", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022088" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0021266" }, { "agency": "NSF", "grant_number": "OAC-2209262" }, { "agency": "J. Yang Family and Foundation" }, { "agency": "Ministero dell'Istruzione, dell'Universit\u00e0 e della Ricerca (MIUR)", "grant_number": "20173B72NB" }, { "agency": "European Research Council (ERC)", "grant_number": "824143" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Liquid-Sunlight-Alliance" } ] }, "doi": "10.1103/physrevresearch.4.043203", "primary_object": { "basename": "PhysRevResearch.4.043203.pdf", "url": "https://authors.library.caltech.edu/records/hk4c3-ncy21/files/PhysRevResearch.4.043203.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Chen, Hsiao-Yi; Sangalli, Davide; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/151wk-93746", "eprint_id": 118850, "eprint_status": "archive", "datestamp": "2023-08-22 18:09:16", "lastmod": "2023-10-23 20:18:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Luo-Yao", "name": { "family": "Luo", "given": "Yao" }, "orcid": "0000-0001-7026-1271" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Predicting Phonon-Induced Spin Decoherence from First Principles: Colossal Spin Renormalization in Condensed Matter", "ispublished": "pub", "full_text_status": "public", "keywords": "General Medicine", "note": "This work was supported by the National Science Foundation under Grants No. DMR-1750613 and QII-TAQS 1936350, which provided for method development, and Grant No. OAC-2209262, which provided for code development. J.\u2009P. acknowledges support by the Korea Foundation for Advanced Studies. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevLett.129.197201.pdf
", "abstract": "Developing a microscopic understanding of spin decoherence is essential to advancing quantum technologies. Electron spin decoherence due to atomic vibrations (phonons) plays a special role as it sets an intrinsic limit to the performance of spin-based quantum devices. Two main sources of phonon-induced spin decoherence\u2014the Elliott-Yafet and Dyakonov-Perel mechanisms\u2014have distinct physical origins and theoretical treatments. Here, we show calculations that unify their modeling and enable accurate predictions of spin relaxation and precession in semiconductors. We compute the phonon-dressed vertex of the spin-spin correlation function with a treatment analogous to the calculation of the anomalous electron magnetic moment in QED. We find that the vertex correction provides a giant renormalization of the electron spin dynamics in solids, greater by many orders of magnitude than the corresponding correction from photons in vacuum. Our Letter demonstrates a general approach for quantitative analysis of spin decoherence in materials, advancing the quest for spin-based quantum technologies.", "date": "2022-11-04", "date_type": "published", "publication": "Physical Review Letters", "volume": "129", "number": "19", "publisher": "American Physical Society", "pagerange": "Art. No. 197201", "id_number": "CaltechAUTHORS:20230118-50862000.2", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230118-50862000.2", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "OAC-1936350" }, { "agency": "NSF", "grant_number": "OAC-2209262" }, { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/physrevlett.129.197201", "primary_object": { "basename": "PhysRevLett.129.197201.pdf", "url": "https://authors.library.caltech.edu/records/151wk-93746/files/PhysRevLett.129.197201.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Park, Jinsoo; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/9tx1c-emw76", "eprint_id": 118233, "eprint_status": "archive", "datestamp": "2023-08-20 08:44:06", "lastmod": "2023-10-23 15:27:32", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Luo-Yao", "name": { "family": "Luo", "given": "Yao" }, "orcid": "0000-0001-7026-1271" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Many-body theory of phonon-induced spin relaxation and decoherence", "ispublished": "pub", "full_text_status": "public", "note": "This work was supported by the National Science Foundation under Grants No. 1750613 and No. 1936350, which provided for method development, and Grant No. 2209262, which provided for code development. J.P. acknowledges support by the Korea Foundation for Advanced Studies. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.106.174404.pdf
", "abstract": "First-principles calculations enable accurate predictions of electronic interactions and dynamics. However, computing the electron spin dynamics remains challenging. The spin-orbit interaction causes various dynamical phenomena that couple with phonons, such as spin precession and spin-flip e-ph scattering, which are difficult to describe with current first-principles calculations. In this work, we show a rigorous framework to study phonon-induced spin relaxation and decoherence, by computing the spin-spin correlation function and its vertex corrections due to e-ph interactions. We apply this approach to a model system and develop corresponding first-principles calculations of spin relaxation in GaAs. Our vertex-correction formalism is shown to capture the Elliott-Yafet, Dyakonov-Perel, and strong-precession mechanisms\u2014three independent spin decoherence regimes with distinct physical origins\u2014thereby unifying their theoretical treatment and calculation. Our method is general and enables quantitative studies of spin relaxation, decoherence, and transport in a wide range of materials and devices.", "date": "2022-11-01", "date_type": "published", "publication": "Physical Review B", "volume": "106", "number": "17", "publisher": "American Physical Society", "pagerange": "Art. No. 174404", "id_number": "CaltechAUTHORS:20221205-666301600.6", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221205-666301600.6", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "OMA-1936350" }, { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/physrevb.106.174404", "primary_object": { "basename": "PhysRevB.106.174404.pdf", "url": "https://authors.library.caltech.edu/records/9tx1c-emw76/files/PhysRevB.106.174404.pdf" }, "resource_type": "article", "pub_year": "2022", "author_list": "Park, Jinsoo; Luo, Yao; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ecckn-yg533", "eprint_id": 113991, "eprint_status": "archive", "datestamp": "2023-08-20 08:08:27", "lastmod": "2023-10-23 23:18:16", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Mitridate-Andrea", "name": { "family": "Mitridate", "given": "Andrea" }, "orcid": "0000-0003-2898-5844" }, { "id": "Trickle-Tanner", "name": { "family": "Trickle", "given": "Tanner" }, "orcid": "0000-0003-1371-4988" }, { "id": "Zhang-Zhengkang", "name": { "family": "Zhang", "given": "Zhengkang" }, "orcid": "0000-0001-8305-5581" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Zurek-K-M", "name": { "family": "Zurek", "given": "Kathryn M." }, "orcid": "0000-0002-2629-337X" } ] }, "title": "Dark matter direct detection in materials with spin-orbit coupling", "ispublished": "pub", "full_text_status": "public", "note": "Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\nFunded by SCOAP3.\n\nReceived 15 March 2022; accepted 13 July 2022; published 25 July 2022. \n\nH.-Y.\u2009C. and M.\u2009B. were supported by the National Science Foundation under Grant No. DMR-1750613. A.\u2009M., T.\u2009T., K.\u2009Z., and Z.\u2009Z. were supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award No. DE-SC0021431, and the Quantum Information Science Enabled Discovery (QuantISED) for High Energy Physics (KA2401032). K.\u2009Z. was also supported by a Simons Investigator Award. Z.\u2009Z. was also supported by the U.S. Department of Energy under the Grant No. DE-SC0011702. The computations presented here were conducted in the Resnick High Performance Computing Center, a facility supported by Resnick Sustainability Institute at the California Institute of Technology.\n\nPublished - PhysRevD.106.015024.pdf
Submitted - 2202.11716.pdf
", "abstract": "Semiconductors with O(meV) band gaps have been shown to be promising targets to search for sub-MeV mass dark matter (DM). In this paper we focus on a class of materials where such narrow band gaps arise naturally as a consequence of spin-orbit coupling (SOC). Specifically, we are interested in computing DM-electron scattering and absorption rates in these materials using state-of-the-art density functional theory techniques. To do this, we extend the DM interaction rate calculation to include SOC effects which necessitates a generalization to spin-dependent wave functions. We apply our new formalism to calculate limits for several DM benchmark models using an example ZrTe\u2085 target and show that the inclusion of SOC can substantially alter projected constraints.", "date": "2022-07-01", "date_type": "published", "publication": "Physical Review D", "volume": "106", "number": "1", "publisher": "American Physical Society", "pagerange": "Art. No. 015024", "id_number": "CaltechAUTHORS:20220322-205046206", "issn": "2470-0010", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220322-205046206", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0021431" }, { "agency": "Department of Energy (DOE)", "grant_number": "KA2401032" }, { "agency": "Simons Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0011702" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "SCOAP3" } ] }, "other_numbering_system": { "items": [ { "id": "2022-007", "name": "CALT-TH" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" }, { "id": "Walter-Burke-Institute-for-Theoretical-Physics" } ] }, "doi": "10.1103/PhysRevD.106.015024", "primary_object": { "basename": "2202.11716.pdf", "url": "https://authors.library.caltech.edu/records/ecckn-yg533/files/2202.11716.pdf" }, "related_objects": [ { "basename": "PhysRevD.106.015024.pdf", "url": "https://authors.library.caltech.edu/records/ecckn-yg533/files/PhysRevD.106.015024.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Chen, Hsiao-Yi; Mitridate, Andrea; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sgg8j-rf755", "eprint_id": 114111, "eprint_status": "archive", "datestamp": "2023-08-20 07:30:45", "lastmod": "2023-10-23 23:22:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Luo-Yao", "name": { "family": "Luo", "given": "Yao" } }, { "id": "Chang-Benjamin-K", "name": { "family": "Chang", "given": "Benjamin K." }, "orcid": "0000-0003-1304-9324" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Comparison of the canonical transformation and energy functional formalisms for ab initio calculations of self-localized polarons", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2022 American Physical Society.\n\nReceived 16 February 2022; accepted 6 April 2022; published 19 April 2022.\n\nThe authors thank Nien-En Lee for fruitful discussions. This work was supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research and Office of Basic Energy Sciences, Scientific Discovery through Advanced Computing (SciDAC) program under Award Number DE-SC0022088. M.B. was partially supported by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0021266. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.105.155132.pdf
Submitted - 2203.00794.pdf
", "abstract": "In materials with strong electron-phonon (e-ph) interactions, charge carriers can distort the surrounding lattice and become trapped, forming self-localized (small) polarons. We recently developed an ab initio approach based on canonical transformations to efficiently compute the formation and energetics of small polarons [N.-E. Lee et al., Phys. Rev. Mater. 5, 063805 (2021)]. A different approach based on a Landau-Pekar energy functional has been proposed in the recent literature [W. H. Sio et al., Phys. Rev. Lett. 122, 246403 (2019); Phys. Rev. B 99, 235139 (2019)]. In this work, we analyze and compare these two methods in detail. We show that the small polaron energy is identical in the two formalisms when using the same polaron wave function. We also show that our canonical transformation formalism can predict polaron band structures and can properly treat zero- and finite-temperature lattice vibration effects, although at present using a fixed polaron wave function. Conversely, the energy functional approach can compute the polaron wave function, but as we show here, it neglects lattice vibrations and cannot address polaron self-localization and thermal band narrowing. Taken together, this work relates two different methods developed recently to study polarons from first-principles, highlighting their merits and shortcomings and discussing them both in a unified formalism.", "date": "2022-04-15", "date_type": "published", "publication": "Physical Review B", "volume": "105", "number": "15", "publisher": "American Physical Society", "pagerange": "Art. No. 155132", "id_number": "CaltechAUTHORS:20220329-173615663", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220329-173615663", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0022088" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0021266" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Liquid-Sunlight-Alliance" } ] }, "doi": "10.1103/PhysRevB.105.155132", "primary_object": { "basename": "2203.00794.pdf", "url": "https://authors.library.caltech.edu/records/sgg8j-rf755/files/2203.00794.pdf" }, "related_objects": [ { "basename": "PhysRevB.105.155132.pdf", "url": "https://authors.library.caltech.edu/records/sgg8j-rf755/files/PhysRevB.105.155132.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Luo, Yao; Chang, Benjamin K.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/acn83-03163", "eprint_id": 114215, "eprint_status": "archive", "datestamp": "2023-08-20 07:16:36", "lastmod": "2023-10-23 23:25:14", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Predicting electron spin decoherence with a many-body first-principles approach", "ispublished": "unpub", "full_text_status": "public", "note": "J.P. thanks Yao Luo for fruitful discussions. This work was supported by the National Science Foundation under Grants No. DMR-1750613 and QII-TAQS 1936350.\n\nAccepted Version - 2203.06401.pdf
", "abstract": "Developing a microscopic understanding of spin decoherence is essential to advancing quantum technologies. Electron spin decoherence due to atomic vibrations (phonons) plays a special role as it sets an intrinsic limit to the performance of spin-based quantum devices. Two main sources of phonon-induced spin decoherence - the Elliott-Yafet (EY) and Dyakonov-Perel (DP) mechanisms - have distinct physical origins and theoretical treatments. Here we show calculations that unify their modeling and enable accurate predictions of spin relaxation and precession in semiconductors. We compute the phonon-dressed vertex of the spin-spin correlation function, with a treatment analogous to the calculation of the anomalous electron magnetic moment in QED. We find that the vertex correction provides a giant renormalization of the electron spin dynamics in solids, greater by many orders of magnitude than the corresponding correction in vacuum. Our work demonstrates a general approach for quantitative analysis of spin decoherence in materials, advancing the quest for spin-based quantum technologies.", "date": "2022-04-12", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20220411-225124081", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220411-225124081", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "OMA-1936350" } ] }, "doi": "10.48550/arXiv.2203.06401", "primary_object": { "basename": "2203.06401.pdf", "url": "https://authors.library.caltech.edu/records/acn83-03163/files/2203.06401.pdf" }, "resource_type": "monograph", "pub_year": "2022", "author_list": "Park, Jinsoo; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/380cm-fw777", "eprint_id": 109890, "eprint_status": "archive", "datestamp": "2023-08-22 15:05:53", "lastmod": "2023-10-23 18:12:27", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chang-Benjamin-K", "name": { "family": "Chang", "given": "Benjamin K." }, "orcid": "0000-0003-1304-9324" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Lee-Nien-En", "name": { "family": "Lee", "given": "Nien-En" }, "orcid": "0000-0002-3172-7750" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Intermediate polaronic charge transport in organic crystals from a many-body first-principles approach", "ispublished": "pub", "full_text_status": "public", "keywords": "Computational methods; Molecular electronics; Physical chemistry; Semiconductors", "note": "\u00a9 2022 The Author(s). Published in partnership with the Shanghai Institute of Ceramics of the Chinese Academy of Sciences. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 13 January 2022; Accepted 24 February 2022; Published 11 April 2022. \n\nThis work was supported by the National Science Foundation under Grant No. DMR-1750613. J.-J.Z. acknowledges support from the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: the development of some computational methods employed in this work was supported through the Office of Science of the US Department of Energy under Award No. DE-SC0004993. N.-E.L. was supported by the Air Force Office of Scientific Research through the Young Investigator Program, Grant FA9550-18-1-0280. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231. \n\nData availability: The data supporting the findings of this study, and in particular the files for the electron-phonon and BTE calculations, are available on Materials Cloud Archive with the identifier doi:10.24435/materialscloud:6t-e0. The authors are available to provide additional data and information upon reasonable request. \n\nCode availability: The PERTURBO code used in this work is an open source software, and can be downloaded at https://perturbo-code.github.io. The BTE subroutines are included in the current release, and the CK subroutines will be included in a future release. \n\nContributions: B.K.C. and M.B. conceived and designed the research. B.K.C. performed calculation and analysis. J.-J.Z. and N.-E.L. provided technical and theoretical support. M.B. supervised the entire research project. All authors discussed the results and contributed to the manuscript. \n\nThe authors declare no competing interests.\n\nPublished - s41524-022-00742-6.pdf
Submitted - 2106.09810.pdf
Supplemental Material - 41524_2022_742_MOESM1_ESM.pdf
", "abstract": "Charge transport in organic molecular crystals (OMCs) is conventionally categorized into two limiting regimes\u2009\u2212\u2009band transport, characterized by weak electron-phonon (e-ph) interactions, and charge hopping due to localized polarons formed by strong e-ph interactions. However, between these two limiting cases there is a less well understood intermediate regime where polarons are present but transport does not occur via hopping. Here we show a many-body first-principles approach that can accurately predict the carrier mobility in this intermediate regime and shed light on its microscopic origin. Our approach combines a finite-temperature cumulant method to describe strong e-ph interactions with Green-Kubo transport calculations. We apply this parameter-free framework to naphthalene crystal, demonstrating electron mobility predictions within a factor of 1.5\u22122 of experiment between 100 and 300\u2009K. Our analysis reveals the formation of a broad polaron satellite peak in the electron spectral function and the failure of the Boltzmann equation in the intermediate regime.", "date": "2022-04-11", "date_type": "published", "publication": "npj Computational Materials", "volume": "8", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 63", "id_number": "CaltechAUTHORS:20210716-222534684", "issn": "2057-3960", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210716-222534684", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1038/s41524-022-00742-6", "primary_object": { "basename": "s41524-022-00742-6.pdf", "url": "https://authors.library.caltech.edu/records/380cm-fw777/files/s41524-022-00742-6.pdf" }, "related_objects": [ { "basename": "2106.09810.pdf", "url": "https://authors.library.caltech.edu/records/380cm-fw777/files/2106.09810.pdf" }, { "basename": "41524_2022_742_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/380cm-fw777/files/41524_2022_742_MOESM1_ESM.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Chang, Benjamin K.; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wwzqc-8b004", "eprint_id": 113085, "eprint_status": "archive", "datestamp": "2023-08-22 13:09:06", "lastmod": "2023-10-23 17:49:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "First-principles ionized-impurity scattering and charge transport in doped materials", "ispublished": "pub", "full_text_status": "public", "keywords": "Physics and Astronomy (miscellaneous); General Materials Science", "note": "\u00a9 2022 American Physical Society. \n\n(Received 12 October 2021; revised 17 December 2021; accepted 4 January 2022; published 24 January 2022) \n\nThis work was supported by the Air Force Office of Scientific Research through the Young Investigator Program Grant No. FA9550-18-1-0280. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231. I-T. L. thanks Dr. Ivan Maliyov and Dr. Cheng-Wei Lee for fruitful discussions.\n\nPublished - PhysRevMaterials.6.L010801.pdf
Submitted - 2110.04920.pdf
Supplemental Material - supinfo.pdf
", "abstract": "Scattering of carriers with ionized impurities governs charge transport in doped semiconductors. However, electron interactions with ionized impurities cannot be fully described with quantitative first-principles calculations, so their understanding relies primarily on simplified models. Here we show an ab initio approach to compute the interactions between electrons and ionized impurities or other charged defects. It includes the short- and long-range electron-defect (e-d) interactions on equal footing, and allows for efficient interpolation of the e-d matrix elements. We combine the e-d and electron-phonon interactions in the Boltzmann transport equation to compute the carrier mobilities in doped silicon over a wide range of temperature and doping concentrations, spanning seamlessly the defect- and phonon-limited transport regimes. The individual contributions of the defect- and phonon-scattering mechanisms to the carrier relaxation times and mean-free paths are analyzed. Our method provides a powerful tool to study electronic interactions in doped materials. It broadens the scope of first-principles transport calculations, enabling studies of a wide range of doped semiconductors and oxides with application to electronics, energy and quantum technologies.", "date": "2022-01", "date_type": "published", "publication": "Physical Review Materials", "volume": "6", "number": "1", "publisher": "American Physical Society", "pagerange": "Art. No. L010801", "id_number": "CaltechAUTHORS:20220124-215251000", "issn": "2475-9953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220124-215251000", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/physrevmaterials.6.l010801", "primary_object": { "basename": "2110.04920.pdf", "url": "https://authors.library.caltech.edu/records/wwzqc-8b004/files/2110.04920.pdf" }, "related_objects": [ { "basename": "PhysRevMaterials.6.L010801.pdf", "url": "https://authors.library.caltech.edu/records/wwzqc-8b004/files/PhysRevMaterials.6.L010801.pdf" }, { "basename": "supinfo.pdf", "url": "https://authors.library.caltech.edu/records/wwzqc-8b004/files/supinfo.pdf" } ], "resource_type": "article", "pub_year": "2022", "author_list": "Lu, I-Te; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/bzms3-zmb46", "eprint_id": 111845, "eprint_status": "archive", "datestamp": "2023-08-22 11:58:56", "lastmod": "2023-10-23 17:49:07", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Truttmann-Tristan-K", "name": { "family": "Truttmann", "given": "Tristan K." }, "orcid": "0000-0003-3016-4340" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Rajapitamahuni-Anil-Kumar", "name": { "family": "Rajapitamahuni", "given": "Anil Kumar" } }, { "id": "Liu-Fengdeng", "name": { "family": "Liu", "given": "Fengdeng" } }, { "id": "Mates-Thomas-E", "name": { "family": "Mates", "given": "Thomas E." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Jalan-Bharat", "name": { "family": "Jalan", "given": "Bharat" }, "orcid": "0000-0002-7940-0490" } ] }, "title": "Combined experimental-theoretical study of electron mobility-limiting mechanisms in SrSnO\u2083", "ispublished": "pub", "full_text_status": "public", "keywords": "Electronic properties and materials; Semiconductors", "note": "\u00a9 The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 19 January 2021; Accepted 22 October 2021; Published 11 November 2021. \n\nThis work was supported by the Air Force Office of Scientific Research (AFOSR) through Grant Nos. FA9550-19-1-0245 and FA9550-21-1-0025. Part of this work was supported by the National Science Foundation through DMR-1741801 and partially by the UMN MRSEC program under Award No. DMR- 2011401. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Work at Caltech was supported as follows: J.-J.Z. was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. M.B. and I.-T.L. were supported by the Air Force Office of Scientific Research through the Young Investigator Program, Grant FA9550-18-1-0280. \n\nData availability: The data that support the findings of this study are available in the manuscript or its Supplementary Information. Other data are available from the corresponding authors (T.K.T. or B.J.) upon reasonable request. \n\nCode availability: All code that was used to generate the findings of this study are available from the references within or otherwise are available from the authors upon reasonable request. \n\nAuthor Contributions: T.T. and F.L. grew and structurally characterized samples. T.T. and A.K.R. performed transport measurements, the data from which were analyzed and fit by T.T., A.K.R., I.-T.L, M.B., and B.J. The first-principles calculations were performed by J.-J.Z. and I.-T.L. under the supervision of M.B. SIMS measurements were performed by T.M. and were analyzed by T.M., T.T., and B.J. All authors discussed, interpreted the results, and prepared the manuscript. B.J. coordinated all aspects of the project. \n\nThe authors declare no competing interests. \n\nPeer review information: Communications Physics thanks the anonymous reviewers for their contribution to the peer review of this work.\n\nTruttmann, T.K., Zhou, JJ., Lu, IT. et al. Publisher Correction: Combined experimental-theoretical study of electron mobility-limiting mechanisms in SrSnO3. Commun Phys 5, 90 (2022). https://doi.org/10.1038/s42005-022-00868-5\n\nPublished - s42005-021-00742-w.pdf
Supplemental Material - 42005_2021_742_MOESM1_ESM.pdf
Erratum - s42005-022-00868-5.pdf
", "abstract": "The discovery and development of ultra-wide bandgap (UWBG) semiconductors is crucial to accelerate the adoption of renewable power sources. This necessitates an UWBG semiconductor that exhibits robust doping with high carrier mobility over a wide range of carrier concentrations. Here we demonstrate that epitaxial thin films of the perovskite oxide Nd_xSr_(1\u2212x)SnO\u2083 (SSO) do exactly this. Nd is used as a donor to successfully modulate the carrier concentration over nearly two orders of magnitude, from 3.7 \u00d7 10\u00b9\u2078 cm\u207b\u00b3 to 2.0 \u00d7 10\u00b2\u2070 cm\u207b\u00b3. Despite being grown on lattice-mismatched substrates and thus having relatively high structural disorder, SSO films exhibited the highest room-temperature mobility, ~70\u2009cm\u00b2\u2009V\u207b\u00b9\u2009s\u207b\u00b9, among all known UWBG semiconductors in the range of carrier concentrations studied. The phonon-limited mobility is calculated from first principles and supplemented with a model to treat ionized impurity and Kondo scattering. This produces excellent agreement with experiment over a wide range of temperatures and carrier concentrations, and predicts the room-temperature phonon-limited mobility to be 76\u201399 cm\u00b2\u2009V\u207b\u00b9\u2009s\u207b\u00b9 depending on carrier concentration. This work establishes a perovskite oxide as an emerging UWBG semiconductor candidate with potential for applications in power electronics.", "date": "2021-11-11", "date_type": "published", "publication": "Communications Physics", "volume": "4", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 241", "id_number": "CaltechAUTHORS:20211111-210019575", "issn": "2399-3650", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211111-210019575", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-19-1-0245" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-21-1-0025" }, { "agency": "NSF", "grant_number": "DMR-1741801" }, { "agency": "NSF", "grant_number": "DMR- 2011401" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1038/s42005-021-00742-w", "primary_object": { "basename": "42005_2021_742_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/bzms3-zmb46/files/42005_2021_742_MOESM1_ESM.pdf" }, "related_objects": [ { "basename": "s42005-021-00742-w.pdf", "url": "https://authors.library.caltech.edu/records/bzms3-zmb46/files/s42005-021-00742-w.pdf" }, { "basename": "s42005-022-00868-5.pdf", "url": "https://authors.library.caltech.edu/records/bzms3-zmb46/files/s42005-022-00868-5.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Truttmann, Tristan K.; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jjjjm-8d431", "eprint_id": 108510, "eprint_status": "archive", "datestamp": "2023-08-20 05:09:14", "lastmod": "2023-10-23 17:06:29", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Timrov-Iurii", "name": { "family": "Timrov", "given": "Iurii" }, "orcid": "0000-0002-6531-9966" }, { "id": "Floris-Andrea", "name": { "family": "Floris", "given": "Andrea" }, "orcid": "0000-0002-3160-6676" }, { "id": "Cococcioni-Matteo", "name": { "family": "Cococcioni", "given": "Matteo" }, "orcid": "0000-0002-1546-3513" }, { "id": "Marzari-Nicola", "name": { "family": "Marzari", "given": "Nicola" }, "orcid": "0000-0002-9764-0199" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab Initio Electron-Phonon Interactions in Correlated Electron Systems", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Physical Society. \n\nReceived 19 February 2021; accepted 12 August 2021; published 16 September 2021. \n\nWork at Caltech was supported by the National Science Foundation under Grant No. DMR-1750613. J.-J.\u2009Z. was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DESC0004993. J.\u2009P. acknowledges support by the Korea Foundation for Advanced Studies. M.\u2009B. was partially supported by the Air Force Office of Scientific Research through the Young Investigator Program Grant No. FA955018-1-0280. M.\u2009C., I.\u2009T., and N.\u2009M. acknowledge support from the EU-H2020 NFFA (Grant Agreement No. 654360). I.\u2009T. and N.\u2009M. also acknowledge support by the Swiss National Science Foundation (SNSF), through Grant No. 200021-179138, and its National Centre of Competence in Research (NCCR) MARVEL.\u2009A.\u2009F. thanks the UK's HEC Materials Chemistry Consortium, funded by EPSRC (EP/L000202, EP/R029431). This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevLett.127.126404.pdf
Submitted - 2102.06840.pdf
Supplemental Material - Supplemental.pdf
", "abstract": "Electron-phonon (e\u2212ph) interactions are pervasive in condensed matter, governing phenomena such as transport, superconductivity, charge-density waves, polarons, and metal-insulator transitions. First-principles approaches enable accurate calculations of e\u2212ph interactions in a wide range of solids. However, they remain an open challenge in correlated electron systems (CES), where density functional theory often fails to describe the ground state. Therefore reliable e\u2212ph calculations remain out of reach for many transition metal oxides, high-temperature superconductors, Mott insulators, planetary materials, and multiferroics. Here we show first-principles calculations of e\u2212ph interactions in CES, using the framework of Hubbard-corrected density functional theory (DFT+U) and its linear response extension (DFPT+U), which can describe the electronic structure and lattice dynamics of many CES. We showcase the accuracy of this approach for a prototypical Mott system, CoO, carrying out a detailed investigation of its e\u2212ph interactions and electron spectral functions. While standard DFPT gives unphysically divergent and short-ranged e\u2212ph interactions, DFPT+U is shown to remove the divergences and properly account for the long-range Fr\u00f6hlich interaction, allowing us to model polaron effects in a Mott insulator. Our work establishes a broadly applicable and affordable approach for quantitative studies of e\u2212ph interactions in CES, a novel theoretical tool to interpret experiments in this broad class of materials.", "date": "2021-09-17", "date_type": "published", "publication": "Physical Review Letters", "volume": "127", "number": "12", "publisher": "American Physical Society", "pagerange": "Art. No. 126404", "id_number": "CaltechAUTHORS:20210322-123709144", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210322-123709144", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA955018-1-0280" }, { "agency": "European Research Council (ERC)", "grant_number": "654360" }, { "agency": "Swiss National Science Foundation (SNSF)", "grant_number": "200021-179138" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "EP/L000202" }, { "agency": "Engineering and Physical Sciences Research Council (EPSRC)", "grant_number": "EP/R029431" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/PhysRevLett.127.126404", "primary_object": { "basename": "Supplemental.pdf", "url": "https://authors.library.caltech.edu/records/jjjjm-8d431/files/Supplemental.pdf" }, "related_objects": [ { "basename": "2102.06840.pdf", "url": "https://authors.library.caltech.edu/records/jjjjm-8d431/files/2102.06840.pdf" }, { "basename": "PhysRevLett.127.126404.pdf", "url": "https://authors.library.caltech.edu/records/jjjjm-8d431/files/PhysRevLett.127.126404.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Zhou, Jin-Jian; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/28vs9-dh779", "eprint_id": 110747, "eprint_status": "archive", "datestamp": "2023-08-20 04:59:22", "lastmod": "2023-10-23 19:50:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Maliyov-Ivan", "name": { "family": "Maliyov", "given": "Ivan" }, "orcid": "0000-0003-4130-6033" }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab initio electron dynamics in high electric fields: Accurate prediction of velocity-field curves", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Physical Society. \n\nReceived 29 June 2021; revised 19 August 2021; accepted 1 September 2021; published 17 September 2021. \n\nI.M. acknowledges support from the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award No. DE-SC0021266. J.P. acknowledges support from the Korea Foundation for Advanced Studies. This letter used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.104.L100303.pdf
Submitted - 2109.01225.pdf
Supplemental Material - Electron-Dynamics-at-High-Fields-Supplemental.pdf
Supplemental Material - Velocity-Field-Curve-GaAs.mp4
", "abstract": "Electron dynamics in external electric fields governs the behavior of solid-state electronic devices. First-principles calculations enable precise predictions of charge transport in low electric fields. However, studies of high-field electron dynamics remain elusive due to a lack of accurate and broadly applicable methods. Here, we develop an efficient approach to solve the real-time Boltzmann transport equation with both the electric field term and ab initio electron-phonon collisions. These simulations provide field-dependent electronic distributions in the time domain, allowing us to investigate both transient and steady-state transport in electric fields ranging from low to high (>10 kV/cm). The broad capabilities of our approach are shown by computing nonequilibrium electron occupations and velocity-field curves in Si, GaAs, and graphene, obtaining results in quantitative agreement with experiment. Our approach sheds light on microscopic details of transport in high electric fields, including the dominant scattering mechanisms and valley occupation dynamics. Our results demonstrate quantitatively accurate calculations of electron dynamics in low to high electric fields, with broad application to power and micro-electronics, optoelectronics, and sensing.", "date": "2021-09-01", "date_type": "published", "publication": "Physical Review B", "volume": "104", "number": "10", "publisher": "American Physical Society", "pagerange": "Art. No. L100303", "id_number": "CaltechAUTHORS:20210907-203710677", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210907-203710677", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0021266" }, { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Liquid-Sunlight-Alliance" } ] }, "doi": "10.1103/PhysRevB.104.L100303", "primary_object": { "basename": "2109.01225.pdf", "url": "https://authors.library.caltech.edu/records/28vs9-dh779/files/2109.01225.pdf" }, "related_objects": [ { "basename": "Electron-Dynamics-at-High-Fields-Supplemental.pdf", "url": "https://authors.library.caltech.edu/records/28vs9-dh779/files/Electron-Dynamics-at-High-Fields-Supplemental.pdf" }, { "basename": "PhysRevB.104.L100303.pdf", "url": "https://authors.library.caltech.edu/records/28vs9-dh779/files/PhysRevB.104.L100303.pdf" }, { "basename": "Velocity-Field-Curve-GaAs.mp4", "url": "https://authors.library.caltech.edu/records/28vs9-dh779/files/Velocity-Field-Curve-GaAs.mp4" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Maliyov, Ivan; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/w5ppg-n5n92", "eprint_id": 101280, "eprint_status": "archive", "datestamp": "2023-08-22 10:17:05", "lastmod": "2023-10-23 16:56:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" } }, { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Maliyov-Ivan", "name": { "family": "Maliyov", "given": "Ivan" } }, { "id": "Tong-Xiao", "name": { "family": "Tong", "given": "Xiao" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Perturbo: A software package for ab initio electron\u2013phonon interactions, charge transport and ultrafast dynamics", "ispublished": "pub", "full_text_status": "public", "keywords": "Charge transport; Ultrafast dynamics; Electron\u2013phonon interactions; Wannier functions", "note": "\u00a9 2021 Elsevier B.V. \n\nReceived 7 February 2020, Accepted 28 February 2021, Available online 22 March 2021. \n\nThe review of this paper was arranged by Prof. D.P. Landau. \n\nWe thank V.A. Jhalani and B.K. Chang for fruitful discussions. This work was supported by the National Science Foundation, United States under Grants No. ACI-1642443 for code development and DMR-1750613 for theory development. J.-J.Z. acknowledges support by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy, United States under Award No. DE-SC0004993. J.P. acknowledges support by the Korea Foundation for Advanced Studies, South Korea. I-T.L. was supported by the Air Force Office of Scientific Research through the Young Investigator Program, Grant FA9550-18-1-0280. X.T. was supported by the Resnick Institute at Caltech. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy, United States under Contract No. DE-AC02-05CH11231. \n\nThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\n\nSubmitted - 2002.02045.pdf
", "abstract": "Perturbo is a software package for first-principles calculations of charge transport and ultrafast carrier dynamics in materials. The current version focuses on electron\u2013phonon interactions and can compute phonon-limited transport properties such as the conductivity, carrier mobility and Seebeck coefficient. It can also simulate the ultrafast nonequilibrium electron dynamics in the presence of electron\u2013phonon scattering. Perturbo uses results from density functional theory and density functional perturbation theory calculations as input, and employs Wannier interpolation to reduce the computational cost. It supports norm-conserving and ultrasoft pseudopotentials, spin\u2013orbit coupling, and polar electron\u2013phonon interactions for bulk and 2D materials. Hybrid MPI plus OpenMP parallelization is implemented to enable efficient calculations on large systems (up to at least 50 atoms) using high-performance computing. Taken together, Perturbo provides efficient and broadly applicable ab initio tools to investigate electron\u2013phonon interactions and carrier dynamics quantitatively in metals, semiconductors, insulators, and 2D materials. \n\nProgram summary: \n\nProgram Title: Perturbo; \n\nCPC Library link to program files: https://doi.org/10.17632/34m2p6v79t.1; \n\nDeveloper's repository link: https://perturbo-code.github.io; \n\nLicensing provisions: GNU General Public Licence 3.0;\n\nProgramming language: Fortran, Python; \n\nExternal routines/libraries: LAPACK, HDF5, MPI, OpenMP, FFTW, Quantum-ESPRESSO, Wannier90; \n\nNature of problem: Computing transport properties from first-principles in materials, including the electrical conductivity, carrier mobility and Seebeck coefficient; Simulating ultrafast nonequilibrium electron dynamics, such as the relaxation of excited carriers via interactions with phonons. \n\nSolution method: We implement the first-principles Boltzmann transport equation, which employs materials properties such as the electronic structure, lattice dynamics, and electron\u2013phonon collision terms computed with density functional theory and density functional perturbation theory. The Boltzmann transport equation is solved numerically to compute charge transport and simulate ultrafast carrier dynamics. Wannier interpolation is employed to reduce the computational cost. \n\nAdditional comments: Hybrid MPI plus OpenMP parallelization is implemented to run large calculations and take advantage of high-performance computing. Most results are output to HDF5 file format, which is portable and convenient for post-processing using high-level languages such as Python and Julia.", "date": "2021-07", "date_type": "published", "publication": "Computer Physics Communications", "volume": "264", "publisher": "Elsevier", "pagerange": "Art. No. 107970", "id_number": "CaltechAUTHORS:20200213-150248226", "issn": "0010-4655", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200213-150248226", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1016/j.cpc.2021.107970", "primary_object": { "basename": "2002.02045.pdf", "url": "https://authors.library.caltech.edu/records/w5ppg-n5n92/files/2002.02045.pdf" }, "resource_type": "article", "pub_year": "2021", "author_list": "Zhou, Jin-Jian; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/jbqwv-pw942", "eprint_id": 105008, "eprint_status": "archive", "datestamp": "2023-08-22 10:08:26", "lastmod": "2023-10-20 21:16:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gao-Shiyuan", "name": { "family": "Gao", "given": "Shiyuan" } }, { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Radiative properties of quantum emitters in boron nitride from excited state calculations and Bayesian analysis", "ispublished": "pub", "full_text_status": "public", "keywords": "Electronic structure; Nanophotonics and plasmonics; Two-dimensional materials", "note": "\u00a9 The Author(s) 2021. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 18 November 2020; Accepted 23 April 2021; Published 04 June 2021. \n\nWe acknowledge valuable discussions with Hamidreza Akbari. This work was supported by the Department of Energy under Grant No. DE-SC0019166. The radiative lifetime code development was partially supported by the National Science Foundation under Grant No. ACI-1642443. H.-Y.C. was partially supported by the J. Yang Fellowship. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231. \n\nData availability: All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Information. Additional data related to this paper may be requested from the authors. \n\nAuthor Contributions: S.G. and M.B. conceived and designed the research. S.G. performed calculation and analysis. H.-Y.C. provided theoretical support. M.B. supervised the entire research project. All authors discussed the results and contributed to the manuscript. \n\nThe authors declare no competing interests.\n\nPublished - s41524-021-00544-2.pdf
Submitted - 2007.10547.pdf
Supplemental Material - 41524_2021_544_MOESM1_ESM.pdf
", "abstract": "Point defects in hexagonal boron nitride (hBN) have attracted growing attention as bright single-photon emitters. However, understanding of their atomic structure and radiative properties remains incomplete. Here we study the excited states and radiative lifetimes of over 20 native defects and carbon or oxygen impurities in hBN using ab initio density functional theory and GW plus Bethe-Salpeter equation calculations, generating a large data set of their emission energy, polarization and lifetime. We find a wide variability across quantum emitters, with exciton energies ranging from 0.3 to 4 eV and radiative lifetimes from ns to ms for different defect structures. Through a Bayesian statistical analysis, we identify various high-likelihood charge-neutral defect emitters, among which the native VNNB defect is predicted to possess emission energy and radiative lifetime in agreement with experiments. Our work advances the microscopic understanding of hBN single-photon emitters and introduces a computational framework to characterize and identify quantum emitters in 2D materials.", "date": "2021-06-04", "date_type": "published", "publication": "npj Computational Materials", "volume": "7", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 85", "id_number": "CaltechAUTHORS:20200818-145940249", "issn": "2057-3960", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200818-145940249", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "J. Yang Fellowship" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1038/s41524-021-00544-2", "primary_object": { "basename": "41524_2021_544_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/jbqwv-pw942/files/41524_2021_544_MOESM1_ESM.pdf" }, "related_objects": [ { "basename": "s41524-021-00544-2.pdf", "url": "https://authors.library.caltech.edu/records/jbqwv-pw942/files/s41524-021-00544-2.pdf" }, { "basename": "2007.10547.pdf", "url": "https://authors.library.caltech.edu/records/jbqwv-pw942/files/2007.10547.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Gao, Shiyuan; Chen, Hsiao-Yi; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/xp74a-j6454", "eprint_id": 106897, "eprint_status": "archive", "datestamp": "2023-08-20 03:24:02", "lastmod": "2023-10-23 15:09:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Nien-En", "name": { "family": "Lee", "given": "Nien-En" }, "orcid": "0000-0002-3172-7750" }, { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Facile ab initio approach for self-localized polarons from canonical transformations", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Physical Society. \n\nReceived 9 November 2020; revised 24 April 2021; accepted 8 June 2021; published 24 June 2021. \n\nThis work was supported by the Air Force Office of Scientific Research through the Young Investigator Program, Grant No. FA9550-18-1-0280. J.-J.Z. was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. H.-Y.C. acknowledges support by the J. Yang Fellowship. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevMaterials.5.063805.pdf
Submitted - 2011.03620.pdf
", "abstract": "Electronic states in a crystal can localize due to strong electron-phonon (e-ph) interactions, forming so-called small polarons. Methods to predict the formation and energetics of small polarons are either computationally costly or not geared toward quantitative predictions. Here we show a formalism based on canonical transformations to compute the polaron formation energy and wave function using ab initio e-ph interactions. Comparison of the calculated polaron and band-edge energies allows us to determine whether charge carriers in a material favor a localized small polaron over a delocalized Bloch state. Due to its low computational cost, our approach enables efficient studies of the formation and energetics of small polarons, as we demonstrate by investigating electron and hole polaron formation in alkali halides and metal oxides and peroxides. We outline refinements of our scheme and extensions to compute transport in the polaron hopping regime.", "date": "2021-06", "date_type": "published", "publication": "Physical Review Materials", "volume": "5", "number": "6", "publisher": "American Physical Society", "pagerange": "Art. No. 063805", "id_number": "CaltechAUTHORS:20201203-151018693", "issn": "2475-9953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201203-151018693", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "J. Yang Family and Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/PhysRevMaterials.5.063805", "primary_object": { "basename": "2011.03620.pdf", "url": "https://authors.library.caltech.edu/records/xp74a-j6454/files/2011.03620.pdf" }, "related_objects": [ { "basename": "PhysRevMaterials.5.063805.pdf", "url": "https://authors.library.caltech.edu/records/xp74a-j6454/files/PhysRevMaterials.5.063805.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Lee, Nien-En; Chen, Hsiao-Yi; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/p9s5b-en862", "eprint_id": 107980, "eprint_status": "archive", "datestamp": "2023-08-20 02:45:18", "lastmod": "2023-10-23 16:22:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Desai-Dhruv-C", "name": { "family": "Desai", "given": "Dhruv C." } }, { "id": "Zviazhynski-Bahdan", "name": { "family": "Zviazhynski", "given": "Bahdan" }, "orcid": "0000-0002-3862-8093" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Magnetotransport in semiconductors and two-dimensional materials from first principles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 American Physical Society. \n\nReceived 19 January 2021; revised 22 March 2021; accepted 23 March 2021; published 7 April 2021. \n\nThis work was supported by the National Science Foundation under Grant No. DMR-1750613. J.-J.Z. acknowledges partial support from the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: The development of some computational methods employed in this work was supported through the Office of Science of the US Department of Energy under Award No. DE-SC0004993. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.103.L161103.pdf
Submitted - 2101.06457.pdf
", "abstract": "We demonstrate a first-principles method to study magnetotransport in materials by solving the Boltzmann transport equation (BTE) in the presence of an external magnetic field. Our approach employs ab initio electron-phonon interactions and takes spin-orbit coupling into account. We apply our method to various semiconductors (Si and GaAs) and two-dimensional (2D) materials (graphene) as representative case studies. The magnetoresistance, Hall mobility, and Hall factor in Si and GaAs are in very good agreement with experiments. In graphene, our method predicts a large magnetoresistance, consistent with experiments. Analysis of the steady-state electron occupations in graphene shows the dominant role of optical phonon scattering and the breaking of the relaxation time approximation. Our paper provides a detailed understanding of the microscopic mechanisms governing magnetotransport coefficients, establishing the BTE in a magnetic field as a broadly applicable first-principles tool to investigate transport in semiconductors and 2D materials.", "date": "2021-04-15", "date_type": "published", "publication": "Physical Review B", "volume": "103", "number": "16", "publisher": "American Physical Society", "pagerange": "Art. No. L161103", "id_number": "CaltechAUTHORS:20210210-082533037", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210210-082533037", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/PhysRevB.103.L161103", "primary_object": { "basename": "2101.06457.pdf", "url": "https://authors.library.caltech.edu/records/p9s5b-en862/files/2101.06457.pdf" }, "related_objects": [ { "basename": "PhysRevB.103.L161103.pdf", "url": "https://authors.library.caltech.edu/records/p9s5b-en862/files/PhysRevB.103.L161103.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Desai, Dhruv C.; Zviazhynski, Bahdan; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3fd4t-eec63", "eprint_id": 105784, "eprint_status": "archive", "datestamp": "2023-08-20 02:28:16", "lastmod": "2023-10-20 22:25:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Tong-Xiao", "name": { "family": "Tong", "given": "Xiao" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Toward precise simulations of the coupled ultrafast dynamics of electrons and atomic vibrations in materials", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2021 Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\nReceived 13 October 2020; accepted 6 April 2021; published 26 April 2021. \n\nThe authors thank Jin-Jian Zhou for fruitful discussions. X.T. thanks the Resnick Sustainability Institute at the California Institute of Technology for fellowship support. This work was partially supported by the National Science Foundation under Grant No. DMR-1750613, which provided for theory development, and by the Department of Energy under Grant No. DE-SC0019166, which provided for numerical calculations and code development. This research used resources of the National Energy Research Scientific Computing Center (NERSC), a US Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevResearch.3.023072.pdf
Submitted - 2009.07958.pdf
Supplemental Material - S1.mov
Supplemental Material - Supplemental-Material.pdf
", "abstract": "Ultrafast spectroscopies can access the dynamics of electrons and nuclei at short timescales, shedding light on nonequilibrium phenomena in materials. However, development of accurate calculations to interpret these experiments has lagged behind as widely adopted simulation schemes are limited to subpicosecond timescales or employ simplified interactions lacking quantitative accuracy. Here we show a precise approach to obtain the time-dependent populations of nonequilibrium electrons and atomic vibrations (phonons) up to tens of picoseconds, with a femtosecond time resolution. Combining first-principles electron-phonon and phonon-phonon interactions with a parallel numerical scheme to time-step the coupled electron and phonon Boltzmann equations, our method provides microscopic insight into scattering mechanisms in excited materials. Focusing on graphene as a case study, we demonstrate calculations of ultrafast electron and phonon dynamics, transient optical absorption, structural snapshots, and diffuse x-ray scattering. Our first-principles approach paves the way for quantitative atomistic simulations of ultrafast dynamics in materials.", "date": "2021-04", "date_type": "published", "publication": "Physical Review Research", "volume": "3", "number": "2", "publisher": "American Physical Society", "pagerange": "Art. No. 023072", "id_number": "CaltechAUTHORS:20201005-102911333", "issn": "2643-1564", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201005-102911333", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/PhysRevResearch.3.023072", "primary_object": { "basename": "2009.07958.pdf", "url": "https://authors.library.caltech.edu/records/3fd4t-eec63/files/2009.07958.pdf" }, "related_objects": [ { "basename": "PhysRevResearch.3.023072.pdf", "url": "https://authors.library.caltech.edu/records/3fd4t-eec63/files/PhysRevResearch.3.023072.pdf" }, { "basename": "S1.mov", "url": "https://authors.library.caltech.edu/records/3fd4t-eec63/files/S1.mov" }, { "basename": "Supplemental-Material.pdf", "url": "https://authors.library.caltech.edu/records/3fd4t-eec63/files/Supplemental-Material.pdf" } ], "resource_type": "article", "pub_year": "2021", "author_list": "Tong, Xiao and Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/q4n3y-8tm47", "eprint_id": 102655, "eprint_status": "archive", "datestamp": "2023-08-19 23:28:31", "lastmod": "2023-10-20 00:23:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jhalani-V-A", "name": { "family": "Jhalani", "given": "Vatsal A." }, "orcid": "0000-0003-0866-0858" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Dreyer-C-E", "name": { "family": "Dreyer", "given": "Cyrus E." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Piezoelectric Electron-Phonon Interaction from Ab Initio Dynamical Quadrupoles: Impact on Charge Transport in Wurtzite GaN", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Physical Society. \n\nReceived 20 February 2020; accepted 27 August 2020; published 21 September 2020. \n\nV.\u2009J. thanks the Resnick Sustainability Institute at Caltech for fellowship support. J.\u2009P. acknowledges support by the Korea Foundation for Advanced Studies. This work was supported by the National Science Foundation under Grants No. DMR-1750613 for theory development and No. ACI-1642443 for code development. J.-J.\u2009Z. acknowledges partial support from the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: the development of some computational methods employed in this work was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. C.\u2009E.\u2009D. acknowledges support from the National Science Foundation under Grant No. DMR-1918455. The Flatiron Institute is a division of the Simons Foundation. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevLett.125.136602.pdf
Submitted - 2002.08351.pdf
Supplemental Material - SuppInfo.pdf
", "abstract": "First-principles calculations of e\u2212ph interactions are becoming a pillar of electronic structure theory. However, the current approach is incomplete. The piezoelectric (PE) e\u2212ph interaction, a long-range scattering mechanism due to acoustic phonons in noncentrosymmetric polar materials, is not accurately described at present. Current calculations include short-range e\u2212ph interactions (obtained by interpolation) and the dipolelike Fr\u00f6lich long-range coupling in polar materials, but lack important quadrupole effects for acoustic modes and PE materials. Here we derive and compute the long-range e\u2212ph interaction due to dynamical quadrupoles, and apply this framework to investigate e\u2212ph interactions and the carrier mobility in the PE material wurtzite GaN. We show that the quadrupole contribution is essential to obtain accurate e\u2212ph matrix elements for acoustic modes and to compute PE scattering. Our work resolves the outstanding problem of correctly computing e\u2212ph interactions for acoustic modes from first principles, and enables studies of e\u2212ph coupling and charge transport in PE materials.", "date": "2020-09-25", "date_type": "published", "publication": "Physical Review Letters", "volume": "125", "number": "13", "publisher": "American Physical Society", "pagerange": "Art. No. 136602", "id_number": "CaltechAUTHORS:20200420-112051827", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200420-112051827", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "DMR-1918455" }, { "agency": "Simons Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/PhysRevLett.125.136602", "primary_object": { "basename": "2002.08351.pdf", "url": "https://authors.library.caltech.edu/records/q4n3y-8tm47/files/2002.08351.pdf" }, "related_objects": [ { "basename": "PhysRevLett.125.136602.pdf", "url": "https://authors.library.caltech.edu/records/q4n3y-8tm47/files/PhysRevLett.125.136602.pdf" }, { "basename": "SuppInfo.pdf", "url": "https://authors.library.caltech.edu/records/q4n3y-8tm47/files/SuppInfo.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Jhalani, Vatsal A.; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/eg0bd-gsc78", "eprint_id": 103291, "eprint_status": "archive", "datestamp": "2023-08-19 23:21:45", "lastmod": "2023-10-20 15:52:57", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" }, "orcid": "0000-0002-1763-5788" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Jhalani-V-A", "name": { "family": "Jhalani", "given": "Vatsal A." }, "orcid": "0000-0003-0866-0858" }, { "id": "Dreyer-C-E", "name": { "family": "Dreyer", "given": "Cyrus E." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Long-range quadrupole electron-phonon interaction from first principles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Physical Society. \n\nReceived 30 March 2020; accepted 29 May 2020; published 21 September 2020. \n\nJ.P. acknowledges support by the Korea Foundation for Advanced Studies. V.A.J. thanks the Resnick Sustainability Institute at Caltech for fellowship support. This work was supported by the National Science Foundation under Grants No. DMR-1750613 for theory development and No. ACI-1642443 for code development. J.-J.Z. acknowledges partial support from the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: the development of some computational methods employed in this work was supported through the Office of Science of the US Department of Energy under Award No. DE-SC0004993. C.E.D. acknowledges support from the National Science Foundation under Grant No. DMR-1918455. The Flatiron Institute is a division of the Simons Foundation. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.102.125203.pdf
Submitted - 2003.13782.pdf
", "abstract": "Lattice vibrations in materials induce perturbations on the electron dynamics in the form of long-range (dipole and quadrupole) and short-range (octopole and higher) potentials. The dipole Fr\u00f6hlich term can be included in current first-principles electron-phonon (e-ph) calculations and is present only in polar materials. The quadrupole e-ph interaction is present in both polar and nonpolar materials, but currently it cannot be computed from first principles. Here we show an approach to compute the quadrupole e-ph interaction and include it in ab initio calculations of e-ph matrix elements. The accuracy of the approach is demonstrated by comparing with direct density functional perturbation theory calculations. We apply our method to silicon as a case of a nonpolar semiconductor and tetragonal PbTiO\u2083 as a case of a polar piezoelectric material. In both materials we find that the quadrupole term strongly impacts the e-ph matrix elements. Analysis of e-ph interactions for different phonon modes reveals that the quadrupole term mainly affects optical modes in silicon and acoustic modes in PbTiO\u2083, although the quadrupole term is needed for all modes to achieve quantitative accuracy. The effect of the quadrupole e-ph interaction on electron scattering processes and transport is shown to be important. Our approach enables accurate studies of e-ph interactions in broad classes of nonpolar, polar, and piezoelectric materials.", "date": "2020-09-15", "date_type": "published", "publication": "Physical Review B", "volume": "102", "number": "12", "publisher": "American Physical Society", "pagerange": "Art. No. 125203", "id_number": "CaltechAUTHORS:20200518-152636389", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200518-152636389", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "DMR-1918455" }, { "agency": "Simons Foundation" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1103/PhysRevB.102.125203", "primary_object": { "basename": "2003.13782.pdf", "url": "https://authors.library.caltech.edu/records/eg0bd-gsc78/files/2003.13782.pdf" }, "related_objects": [ { "basename": "PhysRevB.102.125203.pdf", "url": "https://authors.library.caltech.edu/records/eg0bd-gsc78/files/PhysRevB.102.125203.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Park, Jinsoo; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7zrs5-yed02", "eprint_id": 90820, "eprint_status": "archive", "datestamp": "2023-08-19 23:18:08", "lastmod": "2023-10-19 14:55:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Physical Origin of the One-Quarter Exact Exchange in Density Functional Theory", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 IOP Publishing Ltd. \n\nReceived 6 March 2020; Revised 7 May 2020; Accepted 18 May 2020; Accepted Manuscript online 18 May 2020. \n\nM.B. thanks Nicola Marzari and Fernando Brandao for fruitful discussions. M.B. also thanks Megan Schill for discussion and for help with the initial stage of this project. This work was supported by the National Science Foundation under Grant CAREER no. CAREER-1750613.\n\nSubmitted - 1810.02446v4.pdf
", "abstract": "Exchange interactions are a manifestation of the quantum mechanical nature of the electrons and play a key role in predicting the properties of materials from first principles. In density functional theory (DFT), a widely used approximation to the exchange energy combines fractions of density-based and Hartree\u2013Fock (exact) exchange. This so-called hybrid DFT scheme is accurate in many materials, for reasons that are not fully understood. Here we show that a 1/4 fraction of exact exchange plus a 3/4 fraction of density-based exchange is compatible with a correct quantum mechanical treatment of the exchange energy of an electron pair in the unpolarized electron gas. We also show that the 1/4 exact-exchange fraction mimics a correlation interaction between doubly-excited electronic configurations. The relation between our results and trends observed in hybrid DFT calculations is discussed, along with other implications.", "date": "2020-09-09", "date_type": "published", "publication": "Journal of Physics: Condensed Matter", "volume": "32", "number": "38", "publisher": "IOP", "pagerange": "Art. No. 385501", "id_number": "CaltechAUTHORS:20181112-071407515", "issn": "0953-8984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181112-071407515", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-1750613" } ] }, "doi": "10.1088/1361-648x/ab9409", "primary_object": { "basename": "1810.02446v4.pdf", "url": "https://authors.library.caltech.edu/records/7zrs5-yed02/files/1810.02446v4.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qkghk-dpn70", "eprint_id": 102782, "eprint_status": "archive", "datestamp": "2023-08-19 23:16:09", "lastmod": "2023-10-20 00:30:05", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Sangalli-Davide", "name": { "family": "Sangalli", "given": "Davide" }, "orcid": "0000-0002-4268-9454" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Exciton-Phonon Interaction and Relaxation Times from First Principles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Physical Society. \n\nReceived 25 February 2020; accepted 31 July 2020; published 31 August 2020. \n\nWe thank F. Paleari and A. Marini for a critical reading of the manuscript. This work was supported by the Department of Energy under Grant No. DE-SC0019166, which provided for theory and method development. The code development was supported by the National Science Foundation under Grant No. ACI-1642443. H.-Y.\u2009C. was partially supported by the J. Yang Fellowship at Caltech. D.\u2009S. acknowledges funding from MIUR PRIN Grant No. 20173B72NB and by the European Union's Horizon 2020 research and innovation program (Grants No. 824143 and No. 654360). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevLett.125.107401.pdf
Submitted - 2002.08913.pdf
Supplemental Material - exph_supp.pdf
", "abstract": "Electron-phonon interactions are key to understanding the dynamics of electrons in materials and can be modeled accurately from first principles. However, when electrons and holes form Coulomb-bound states (excitons), quantifying their interactions and scattering processes with phonons remains an open challenge. Here we show a rigorous approach for computing exciton-phonon (ex-ph) interactions and the associated exciton dynamical processes from first principles. Starting from the ab initio Bethe-Salpeter equation, we derive expressions for the ex-ph matrix elements and relaxation times. We apply our method to bulk hexagonal boron nitride, for which we map the ex-ph relaxation times as a function of exciton momentum and energy, analyze the temperature and phonon-mode dependence of the ex-ph scattering processes, and accurately predict the phonon-assisted photoluminescence. The approach introduced in this work is general and provides a framework for investigating exciton dynamics in a wide range of materials.", "date": "2020-09-04", "date_type": "published", "publication": "Physical Review Letters", "volume": "125", "number": "10", "publisher": "American Physical Society", "pagerange": "Art. No. 107401", "id_number": "CaltechAUTHORS:20200427-081647714", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200427-081647714", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Caltech" }, { "agency": "Ministero dell'Istruzione, dell'Universita e della Ricerca (MIUR)", "grant_number": "20173B72NB" }, { "agency": "European Research Council (ERC)", "grant_number": "824143" }, { "agency": "European Research Council (ERC)", "grant_number": "654360" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/PhysRevLett.125.107401", "primary_object": { "basename": "2002.08913.pdf", "url": "https://authors.library.caltech.edu/records/qkghk-dpn70/files/2002.08913.pdf" }, "related_objects": [ { "basename": "PhysRevLett.125.107401.pdf", "url": "https://authors.library.caltech.edu/records/qkghk-dpn70/files/PhysRevLett.125.107401.pdf" }, { "basename": "exph_supp.pdf", "url": "https://authors.library.caltech.edu/records/qkghk-dpn70/files/exph_supp.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Chen, Hsiao-Yi; Sangalli, Davide; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/mm7ef-wrg56", "eprint_id": 102171, "eprint_status": "archive", "datestamp": "2023-08-22 04:26:31", "lastmod": "2023-10-19 23:55:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Nien-En", "name": { "family": "Lee", "given": "Nien-En" }, "orcid": "0000-0002-3172-7750" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab initio electron-two-phonon scattering in GaAs from next-to-leading order perturbation theory", "ispublished": "pub", "full_text_status": "public", "keywords": "Computational methods; Electronic properties and materials; Electronic structure; Semiconductors", "note": "\u00a9 2020 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 11 April 2019; Accepted 02 March 2020; Published 30 March 2020. \n\nThis work was supported by the Air Force Office of Scientific Research through the Young Investigator Program Grant FA9550-18-1-0280. J.-J.Z. and H.-Y.C. were supported by the National Science Foundation under Grant No. ACI- 1642443, which provided for code development. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. \n\nData availability: The data that support the findings of this study are available from the corresponding author upon reasonable request. \n\nCode availability: The code employed in this work, Perturbo, is available for download at https://perturbo-code.github.io/. The 2ph routines developed in this work are available from the corresponding author upon reasonable request. \n\nAuthor Contributions: M.B. conceived the research. N.-E.L. derived the analytic expressions, implemented the code and carried out the numerical calculations. J.-J.Z. helped with code development. H.-Y.C. helped deriving the equations. N.-E.L. and M.B. wrote the manuscript. All authors contributed to analyzing the results and editing the manuscript. \n\nThe authors declare no competing interests.\n\nPublished - s41467-020-15339-0.pdf
Supplemental Material - 41467_2020_15339_MOESM1_ESM.pdf
", "abstract": "Electron-phonon (e\u2013ph) interactions are usually treated in the lowest order of perturbation theory. Here we derive next-to-leading order e\u2013ph interactions, and compute from first principles the associated electron-two-phonon (2ph) scattering rates. The derivations involve Matsubara sums of two-loop Feynman diagrams, and the numerical calculations are challenging as they involve Brillouin zone integrals over two crystal momenta and depend critically on the intermediate state lifetimes. Using Monte Carlo integration together with a self-consistent update of the intermediate state lifetimes, we compute and converge the 2ph scattering rates, and analyze their energy and temperature dependence. We apply our method to GaAs, a weakly polar semiconductor with dominant optical-mode long-range e\u2013ph interactions. We find that the 2ph scattering rates are as large as nearly half the value of the one-phonon rates, and that including the 2ph processes is necessary to accurately predict the electron mobility in GaAs from first principles.", "date": "2020-03-30", "date_type": "published", "publication": "Nature Communications", "volume": "11", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 1607", "id_number": "CaltechAUTHORS:20200330-125817019", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200330-125817019", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1038/s41467-020-15339-0", "pmcid": "PMC7105459", "primary_object": { "basename": "41467_2020_15339_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/mm7ef-wrg56/files/41467_2020_15339_MOESM1_ESM.pdf" }, "related_objects": [ { "basename": "s41467-020-15339-0.pdf", "url": "https://authors.library.caltech.edu/records/mm7ef-wrg56/files/s41467-020-15339-0.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Lee, Nien-En; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yrf4d-ms970", "eprint_id": 100024, "eprint_status": "archive", "datestamp": "2023-08-22 04:21:15", "lastmod": "2023-10-18 19:00:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" } }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab initio electron-defect interactions using Wannier functions", "ispublished": "pub", "full_text_status": "public", "keywords": "Applied physics; Atomistic models; Computational methods; Electronic properties and materials", "note": "\u00a9 2020 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived 30 October 2019; Accepted 19 February 2020; Published 12 March 2020. \n\nThis work was supported by the Air Force Office of Scientific Research through the Young Investigator Program, grant FA9550-18-1-0280. J.-J.Z. was supported by the National Science Foundation under grant number ACI-1642443, which provided for code development, and CAREER-1750613, which provided for part of the theory development. J.P. acknowledges support by the Korea Foundation for Advanced Studies. \n\nData availability: The data that support the findings of this study are available from the corresponding author upon reasonable request. \n\nCode availability: The code developed in this work will be released in the future at http://perturbo.caltech.edu/. \n\nAuthor Contributions: I.-T.L. derived the equations, implemented the code, and carried out the numerical calculations. J.P. and J.-J.Z. contributed to developing the code. M.B. supervised the research. M.B. and I.-T.L. analyzed the results and wrote the manuscript. All authors edited the manuscript. \n\nThe authors declare no competing interests.\n\nPublished - s41524-020-0284-y.pdf
Submitted - 1910.14516.pdf
Supplemental Material - 41524_2020_284_MOESM1_ESM.pdf
", "abstract": "Computing electron\u2013defect (e\u2013d) interactions from first principles has remained impractical due to computational cost. Here we develop an interpolation scheme based on maximally localized Wannier functions (WFs) to efficiently compute e\u2013d interaction matrix elements. The interpolated matrix elements can accurately reproduce those computed directly without interpolation and the approach can significantly speed up calculations of e\u2013d relaxation times and defect-limited charge transport. We show example calculations of neutral vacancy defects in silicon and copper, for which we compute the e\u2013d relaxation times on fine uniform and random Brillouin zone grids (and for copper, directly on the Fermi surface), as well as the defect-limited resistivity at low temperature. Our interpolation approach opens doors for atomistic calculations of charge carrier dynamics in the presence of defects.", "date": "2020-03-12", "date_type": "published", "publication": "npj Computational Materials", "volume": "6", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 17", "id_number": "CaltechAUTHORS:20191125-093120756", "issn": "2057-3960", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191125-093120756", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Korea Foundation for Advanced Studies" } ] }, "doi": "10.1038/s41524-020-0284-y", "primary_object": { "basename": "1910.14516.pdf", "url": "https://authors.library.caltech.edu/records/yrf4d-ms970/files/1910.14516.pdf" }, "related_objects": [ { "basename": "41524_2020_284_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/yrf4d-ms970/files/41524_2020_284_MOESM1_ESM.pdf" }, { "basename": "s41524-020-0284-y.pdf", "url": "https://authors.library.caltech.edu/records/yrf4d-ms970/files/s41524-020-0284-y.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Lu, I-Te; Park, Jinsoo; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/wf6s3-za481", "eprint_id": 99475, "eprint_status": "archive", "datestamp": "2023-08-19 20:00:57", "lastmod": "2023-10-18 18:20:17", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jhalani-Vatsal-A", "name": { "family": "Jhalani", "given": "Vatsal A." }, "orcid": "0000-0003-0866-0858" }, { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Precise radiative lifetimes in bulk crystals from first principles: the case of wurtzite gallium nitride", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 IOP Publishing Ltd. \n\nReceived 5 September 2019; Revised 22 October 2019; Accepted 7 November 2019; Accepted Manuscript online 7 November 2019.\n\nThe authors thank Davide Sangalli for fruitful discussions. V.A.J. thanks the Resnick Sustainability Institute at Caltech for fellowship support. This work was partially supported by the Department of Energy under Grant No. de-sc0019166, which provided for theory and method development, and by the National Science Foundation under Grant No. ACI-1642443, which provided for code development. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. M.P. thanks CINECA for computational resources.\n\nSubmitted - 1908.09962.pdf
", "abstract": "Gallium nitride (GaN) is a key semiconductor for solid-state lighting, but its radiative processes are not fully understood. Here we show a first-principles approach to accurately compute the radiative lifetimes in bulk uniaxial crystals, focusing on wurtzite GaN. Our computed radiative lifetimes are in very good agreement with experiment up to 100 K. We show that taking into account excitons (through the Bethe-Salpeter equation) and spin-orbit coupling to include the exciton fine structure is essential for computing accurate radiative lifetimes. A model for exciton dissociation into free carriers allows us to compute the radiative lifetimes up to room temperature. Our work enables precise radiative lifetime calculations in III-nitrides and other anisotropic solid-state emitters.", "date": "2020-02-20", "date_type": "published", "publication": "Journal of Physics: Condensed Matter", "volume": "32", "number": "8", "publisher": "IOP", "pagerange": "Art. No. 084001", "id_number": "CaltechAUTHORS:20191025-161427443", "issn": "0953-8984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191025-161427443", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1088/1361-648x/ab5563", "primary_object": { "basename": "1908.09962.pdf", "url": "https://authors.library.caltech.edu/records/wf6s3-za481/files/1908.09962.pdf" }, "resource_type": "article", "pub_year": "2020", "author_list": "Jhalani, Vatsal A.; Chen, Hsiao-Yi; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sazsr-d7z34", "eprint_id": 97659, "eprint_status": "archive", "datestamp": "2023-08-19 19:35:42", "lastmod": "2023-10-18 16:11:11", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Park-Jinsoo", "name": { "family": "Park", "given": "Jinsoo" } }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Spin-phonon relaxation times in centrosymmetric materials from first principles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2020 American Physical Society. \n\nReceived 3 June 2019; revised manuscript received 4 November 2019; published 13 January 2020. \n\nJ.P. thanks Raffaello Bianco and I-Te Lu for fruitful discussions. J.P. acknowledges support by the Korea Foundation for Advanced Studies. This work was supported by the National Science Foundation under Grants No. CAREER-1750613, which provided for theory and method development, and No. ACI-1642443, which provided for code development. M.B. was partially supported by the Department of Energy under Grant No. DE-SC0019166.\n\nPublished - PhysRevB.101.045202.pdf
Submitted - 1906.01109.pdf
Supplemental Material - Supplemental.pdf
", "abstract": "We present a first-principles approach for computing the phonon-limited T\u2081 spin relaxation time due to the Elliott-Yafet mechanism. Our scheme combines fully relativistic spin-flip electron-phonon interactions with an approach to compute the effective spin of band electrons in materials with inversion symmetry. We apply our method to silicon and diamond, for which we compute the temperature dependence of the spin relaxation times and analyze the contributions to spin relaxation from different phonons and valley processes. The computed spin relaxation times in silicon are in excellent agreement with experiment in the 50\u2013300 K temperature range. In diamond, we predict intrinsic spin relaxation times of 540 \u03bcs at 77 K and 2.3 \u03bcs at 300 K. We show that the spin-flip and momentum relaxation mechanisms are governed by distinct microscopic processes. Our work enables precise predictions of spin-phonon relaxation times in a wide range of materials, providing microscopic insight into spin relaxation and guiding the development of spin-based quantum technologies.", "date": "2020-01-15", "date_type": "published", "publication": "Physical Review B", "volume": "101", "number": "4", "publisher": "American Physical Society", "pagerange": "Art. No. 045202", "id_number": "CaltechAUTHORS:20190805-135231900", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190805-135231900", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Korea Foundation for Advanced Studies" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" } ] }, "doi": "10.1103/physrevb.101.045202", "primary_object": { "basename": "1906.01109.pdf", "url": "https://authors.library.caltech.edu/records/sazsr-d7z34/files/1906.01109.pdf" }, "related_objects": [ { "basename": "PhysRevB.101.045202.pdf", "url": "https://authors.library.caltech.edu/records/sazsr-d7z34/files/PhysRevB.101.045202.pdf" }, { "basename": "Supplemental.pdf", "url": "https://authors.library.caltech.edu/records/sazsr-d7z34/files/Supplemental.pdf" } ], "resource_type": "article", "pub_year": "2020", "author_list": "Park, Jinsoo; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h69cv-y1188", "eprint_id": 100487, "eprint_status": "archive", "datestamp": "2023-08-19 17:28:54", "lastmod": "2023-10-18 20:35:04", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jhalani-V-A", "name": { "family": "Jhalani", "given": "Vatsal A." }, "orcid": "0000-0003-0866-0858" }, { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "First-Principles Exciton Radiative Lifetimes in Wurtzite GaN", "ispublished": "unpub", "full_text_status": "public", "note": "The authors thank Davide Sangalli for fruitful discussions. V.A.J. thanks the Resnick Sustainability Institute at Caltech for fellowship support. This work was partially supported by the Department of Energy under Grant No. de-sc0019166, which provided for theory and method development, and by the National Science Foundation under Grant No. ACI-1642443, which provided for code development. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. M.P. thanks CINECA for computational resources.\n\nSubmitted - 1908.09962.pdf
", "abstract": "Gallium nitride (GaN) is a key semiconductor for solid-state lighting, but its radiative processes are not fully understood. Here we show a first-principles approach to accurately compute the radiative lifetimes in bulk uniaxial crystals, focusing on wurtzite GaN. Our computed radiative lifetimes are in very good agreement with experiment up to 100 K. We show that taking into account excitons (through the Bethe-Salpeter equation) and spin-orbit coupling to include the exciton fine structure is essential for computing accurate radiative lifetimes. A model for exciton dissociation into free carriers allows us to compute the radiative lifetimes up to room temperature. Our work enables precise radiative lifetime calculations in III-nitrides and other anisotropic solid-state emitters.", "date": "2020-01-08", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20200103-093928953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200103-093928953", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.48550/arXiv.1908.09962", "primary_object": { "basename": "1908.09962.pdf", "url": "https://authors.library.caltech.edu/records/h69cv-y1188/files/1908.09962.pdf" }, "resource_type": "monograph", "pub_year": "2020", "author_list": "Jhalani, Vatsal A.; Chen, Hsiao-Yi; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7a3j3-9c465", "eprint_id": 99476, "eprint_status": "archive", "datestamp": "2023-08-19 18:54:46", "lastmod": "2023-10-18 18:20:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Predicting Charge Transport in the Presence of Polarons: The Beyond-Quasiparticle Regime in SrTiO\u2083", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. \n\nReceived 26 August 2019; revised manuscript received 17 October 2019; published 2 December 2019. \n\nJ.-J.Z. has benefited from discussion with N.-E. Lee. This work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. M.B. acknowledges support by the National Science Foundation under Grant No. ACI-1642443, which provided for code development, and Grant No. CAREER-1750613, which provided for theory and method development. This work was partially supported by the Air Force Office of Scientific Research through the Young Investigator Program, Grant FA9550-18-1-0280. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevResearch.1.033138.pdf
Submitted - 1905.03414.pdf
", "abstract": "In materials with strong electron-phonon (e\u2212ph) interactions, the electrons carry a phonon cloud during their motion, forming quasiparticles known as polarons. Predicting charge transport and its temperature dependence in the polaron regime remains an open challenge. Here, we present first-principles calculations of charge transport in a prototypical material with large polarons, SrTiO\u2083. Using a cumulant diagram-resummation technique that can capture the strong e\u2212ph interactions, our calculations can accurately predict the experimental electron mobility in SrTiO\u2083 between 150\u2013300 K. They further reveal that for increasing temperature the charge transport mechanism transitions from bandlike conduction, in which the scattering of renormalized quasiparticles is dominant, to a beyond-quasiparticle transport regime governed by incoherent contributions due to the interactions between the electrons and their phonon cloud. Our work reveals long-sought microscopic details of charge transport in SrTiO\u2083, and provides a broadly applicable method for predicting charge transport in materials with strong e\u2212ph interactions and polarons.", "date": "2019-12", "date_type": "published", "publication": "Physical Review Research", "volume": "1", "number": "3", "publisher": "American Physical Society", "pagerange": "Art. No. 033138", "id_number": "CaltechAUTHORS:20191025-161728302", "issn": "2643-1564", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191025-161728302", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/PhysRevResearch.1.033138", "primary_object": { "basename": "1905.03414.pdf", "url": "https://authors.library.caltech.edu/records/7a3j3-9c465/files/1905.03414.pdf" }, "related_objects": [ { "basename": "PhysRevResearch.1.033138.pdf", "url": "https://authors.library.caltech.edu/records/7a3j3-9c465/files/PhysRevResearch.1.033138.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Zhou, Jin-Jian and Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/k2dar-btc26", "eprint_id": 99481, "eprint_status": "archive", "datestamp": "2023-08-19 20:20:15", "lastmod": "2023-10-18 18:20:34", "type": "thesis", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Novel materials, computational spectroscopy, and multiscale simulation in nanoscale photovoltaics", "ispublished": "unpub", "full_text_status": "public", "note": "Submitted to the Department of Materials Science and Engineering on May 1, 2013 in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Materials Science and Engineering.\n\nAccepted Version - 861621158-MIT.pdf
", "abstract": "Photovoltaic (PV) solar cells convert solar energy to electricity using combinations of semiconducting sunlight absorbers and metallic materials as electrical contacts. Novel nanoscale materials introduce new paradigms for ultrathin, lightweight, solution processable PV as an alternative to conventional Si technology. For example, the ability to use deposition methods not viable in conventional inorganic PV is particularly exciting as products like paper, textiles, automobiles, and building materials could be coated with PV devices, thus making solar cells ubiquitous. In addition, the optical absorption, band gap, and charge carrier mobility of nanoscale materials can be tuned by tailoring their chemistry or using quantum confinement effects, thus creating novel opportunities for efficient and inexpensive solar cells. From the viewpoint of the fundamental processes involved in PV operation, nanoscale PV poses additional challenges due to the formation of strongly bound electron-hole pairs (excitons) upon photoabsorption requiring the presence of semiconductor heterointerfaces within the active layer to dissociate excitons and generate charge carriers. Such interfaces are known as donor-acceptor (D-A) interfaces, and their presence leads to correlated exciton and charge dynamics in nanoscale PV. Material combinations suitable for nanoscale PV can be predicted using atomistic quantum mechanical calculations, which further enable the computation of a small number of spectroscopic quantities necessary to estimate the power conversion efficiency. Our work shows the computational design of two novel classes of materials for nanoscale PV displaying optical absorption, stability, tunability, and carrier mobility superior to materials employed so far in nanoscale PV. To this end, we employed simulation techniques generally falling under the umbrella of ab initio atomistic electronic structure methods, including density functional theory (DFT) and the GW-Bethe-Salpeter approach. Proof-of-concept PV devices were fabricated and tested within our group and in collaboration with other experimental research groups. The two material families studied in this thesis include carbon based materials (both in nanoscale and bulk form) and two-dimensional monolayers such as graphene, reduced graphene oxide, boron nitride, and transition metal dichalcogenides. Our work demonstrates the feasibility of novel PV devices with a range of benefits employing such materials. It further develops a framework to accurately predict exciton dissociation at D-A interfaces and estimate efficiencies in nanoscale PV. Beyond our work on nanoscale materials, we introduce a combination of methods to enable simulation of nanoscale PV across time and length scales. We discuss modeling of subpicosecond dynamics at D-A interfaces, device-scale transport of excitons, charge carriers, and photons, and macroscopic sunlight management by arranging solar panels to best couple with the Sun's trajectory. We elaborate on the latter point and discuss our work on simulation and fabrication of macroscopic three-dimensional PV structures with promise to deliver a range of benefits for solar energy conversion, including reduced seasonal and latitude sensitivity and a doubling of peak power generation hours. Taken together, this thesis advances the computational design of nanoscale PV systems and introduces novel families of materials and PV structures with technological promise for next-generation PV. This thesis document is organized as follows: Chapter 1 and Chapter 2 introduce, respectively, nanoscale PV and ab initio atomistic simulation methods employed in this work. Chapter 3 is the core of our work on novel families of materials for nanoscale PV, and Chapter 4 illustrates multi-scale simulation methods in nanoscale PV as well as our work on three-dimensional PV. The key results are briefly summarized in Chapter 5.", "date": "2019-10-28", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20191028-084857859", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191028-084857859", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "primary_object": { "basename": "861621158-MIT.pdf", "url": "https://authors.library.caltech.edu/records/k2dar-btc26/files/861621158-MIT.pdf" }, "resource_type": "thesis", "pub_year": "2019", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/hgx98-c7q35", "eprint_id": 95063, "eprint_status": "archive", "datestamp": "2023-08-19 17:20:34", "lastmod": "2023-10-20 18:31:26", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Jhalani-V-A", "name": { "family": "Jhalani", "given": "Vatsal A." }, "orcid": "0000-0003-0866-0858" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab Initio Calculations of Exciton Radiative Lifetimes in Bulk Crystals, Nanostructures and Molecules", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Physical Society. \n\nReceived 25 January 2019; revised manuscript received 26 July 2019; published 16 August 2019. \n\nThe authors thank Davide Sangalli for fruitful discussions. This work was partially supported by the Department of Energy under Grant No. DE-SC0019166, which provided for theory and method development, and by the National Science Foundation under Grant No. ACI-1642443, which provided for code development. M.P. acknowledges the Tor Vergata University for financial support through the mission sustainability project 2DUTOPI. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.100.075135.pdf
Submitted - 1901.08747.pdf
", "abstract": "Excitons are bound electron-hole pairs that dominate the optical response of semiconductors and insulators, especially in materials where the Coulomb interaction is weakly screened. Light absorption (including excitonic effects) has been studied extensively using first-principles calculations, but methods for computing radiative recombination and light emission are still being developed. Here we show a unified ab initio approach to compute exciton radiative recombination in materials ranging from bulk crystals to nanostructures and molecules. We derive the rate of exciton radiative recombination in bulk crystals, isolated systems, and in one- and two-dimensional materials, using Fermi's golden rule within the Bethe-Salpeter equation approach. We present benchmark calculations of radiative lifetimes in a GaAs crystal and in gas-phase organic molecules. Our work provides a general method for studying exciton recombination and light emission in bulk, nanostructured, and molecular materials from first principles.", "date": "2019-08-15", "date_type": "published", "publication": "Physical Review B", "volume": "100", "number": "7", "publisher": "American Physical Society", "pagerange": "Art. No. 075135", "id_number": "CaltechAUTHORS:20190429-081350448", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190429-081350448", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0019166" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Tor Vergata University", "grant_number": "2DUTOPI" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/PhysRevB.100.075135", "primary_object": { "basename": "1901.08747.pdf", "url": "https://authors.library.caltech.edu/records/hgx98-c7q35/files/1901.08747.pdf" }, "related_objects": [ { "basename": "PhysRevB.100.075135.pdf", "url": "https://authors.library.caltech.edu/records/hgx98-c7q35/files/PhysRevB.100.075135.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Chen, Hsiao-Yi; Jhalani, Vatsal A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/j5bpp-2ek09", "eprint_id": 93857, "eprint_status": "archive", "datestamp": "2023-08-19 15:57:23", "lastmod": "2023-10-20 17:28:25", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Martinolich-A-J", "name": { "family": "Martinolich", "given": "Andrew J." }, "orcid": "0000-0002-7866-9594" }, { "id": "Lee-Cheng-Wei", "name": { "family": "Lee", "given": "Cheng-Wei" } }, { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Bevilacqua-S-C", "name": { "family": "Bevilacqua", "given": "Sarah C." }, "orcid": "0000-0002-6834-7145" }, { "id": "Preefer-M-B", "name": { "family": "Preefer", "given": "Molleigh B." }, "orcid": "0000-0002-3699-8613" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Schleife-A", "name": { "family": "Schleife", "given": "Andr\u00e9" }, "orcid": "0000-0003-0496-8214" }, { "id": "See-Kimberly-A", "name": { "family": "See", "given": "Kimberly A." }, "orcid": "0000-0002-0133-9693" } ] }, "title": "Solid-State Divalent Ion Conduction in ZnPS_3", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Chemical Society. \n\nReceived: January 16, 2019; Revised: February 28, 2019; Publication Date (Web): March 15, 2019. \n\nFinancial support from Caltech and the Dow Next Generation Educator Fund is gratefully acknowledged. A.J.M. acknowledges postdoctoral fellowship from the Resnick Sustainability Institute at Caltech. M.B.P. acknowledges support from the Mellichamp Sustainability Fellowship at UCSB. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. I.-T.L. was supported by the Air Force Office of Scientific Research through the Young Investigator Program Grant FA9550-18-1-0280. A.S. acknowledges support from the National Science Foundation under Grant No. DMR-1555153. This work made use of the Illinois Campus Cluster, a computing resource operated by the Illinois Campus Cluster Program (ICCP) in conjunction with the National Center for Supercomputing Applications (NCSA) supported by funds from the University of Illinois at Urbana-Champaign. This research is part of the Blue Waters sustained-petascale computing project, which is supported by the National Science Foundation (awards OCI-0725070 and ACI-1238993) and the state of Illinois. Blue Waters is a joint effort of the University of Illinois at Urbana-Champaign and its National Center for Supercomputing Applications. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE- AC02-05CH11231. The authors thank Dr. Chi Ma for assistance in the collection of SEM images and Dr. Sonjong Hwang for assistance in the collection of NMR spectra. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - cm9b00207_si_001.pdf
", "abstract": "Next-generation batteries based on divalent working ions have the potential to both reduce the cost of energy storage devices and increase performance. Examples of promising divalent systems include those based on Mg^(2+), Ca^(2+), and Zn^(2+) working ions. Development of such technologies is slow, however, in part due to the difficulty associated with divalent cation conduction in the solid state. Divalent ion conduction is especially challenging in insulating materials that would be useful as solid-state electrolytes or protecting layers on the surfaces of metal anodes. Furthermore, there are no reports of divalent cation conduction in insulating, inorganic materials at reasonable temperatures, prohibiting the development of structure\u2013property relationships. Here, we report Zn^(2+) conduction in insulating ZnPS_3, demonstrating divalent ionic conductivity in an ordered, inorganic lattice near room temperature. Importantly, the activation energy associated with the bulk conductivity is low, 351 \u00b1 99 meV, comparable to some Li+conductors such as LTTO, although not as low as the superionic Li+ conductors. First-principles calculations suggest that the barrier corresponds to vacancy-mediated diffusion. Assessment of the structural distortions observed along the ion diffusion pathways suggests that an increase in the P\u2013P\u2013S bond angle in the [P_2S_6]^(4\u2013) moiety accommodates the Zn^(2+) as it passes through the high-energy intermediate coordination environments. ZnPS_3 now represents a baseline material family to begin developing the structure\u2013property relationships that control divalent ion diffusion and conduction in insulating solid-state hosts.", "date": "2019-05-28", "date_type": "published", "publication": "Chemistry of Materials", "volume": "31", "number": "10", "publisher": "American Chemical Society", "pagerange": "3652-3661", "id_number": "CaltechAUTHORS:20190315-083524097", "issn": "0897-4756", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190315-083524097", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "Dow Next Generation Educator Fund" }, { "agency": "Resnick Sustainability Institute" }, { "agency": "University of California, Santa Barbara" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-06CH11357" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "NSF", "grant_number": "DMR-1555153" }, { "agency": "University of Illinois Urbana-Champaign" }, { "agency": "NSF", "grant_number": "OCI-0725070" }, { "agency": "NSF", "grant_number": "ACI-1238993" }, { "agency": "State of Illinois" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acs.chemmater.9b00207", "primary_object": { "basename": "cm9b00207_si_001.pdf", "url": "https://authors.library.caltech.edu/records/j5bpp-2ek09/files/cm9b00207_si_001.pdf" }, "resource_type": "article", "pub_year": "2019", "author_list": "Martinolich, Andrew J.; Lee, Cheng-Wei; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sd3bm-bss62", "eprint_id": 95418, "eprint_status": "archive", "datestamp": "2023-08-19 14:57:39", "lastmod": "2023-10-20 20:12:59", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Nien-En", "name": { "family": "Lee", "given": "Nien-En" }, "orcid": "0000-0002-3172-7750" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Next-to-Leading Order Ab Initio Electron-Phonon Scattering", "ispublished": "unpub", "full_text_status": "public", "note": "This work was supported by the Air Force Office of Scientific Research through the Young Investigator Program Grant FA9550-18-1-0280. J.-J. Z. and H.-Y. C. were supported by the National Science Foundation under Grant No. ACI-1642443, which provided for code development. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nSubmitted - 1903.08261.pdf
", "abstract": "Electron-phonon (e-ph) interactions are usually treated in the lowest order of perturbation theory. Here we derive next-to-leading order e-ph interactions, and compute from first principles the associated two-phonon e-ph scattering rates. The derivation involves Matsubara sums of the relevant two-loop Feynman diagrams, and the numerical calculations are challenging since they involve Brillouin zone integrals over two crystal momenta and depend critically on the intermediate state lifetimes. Using random grids and Monte Carlo integration, together with a self-consistent update of the intermediate state lifetimes, we compute and converge the two-phonon scattering rates, using GaAs as a case study. For the longitudinal optical phonon in GaAs, we find that the two-phonon scattering rates are as large as nearly half the value of the leading-order rates. The energy and temperature dependence of the two-phonon processes are analyzed. We show that including the two-phonon processes is important to accurately predicting the electron mobility in GaAs.", "date": "2019-05-13", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20190513-080918730", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190513-080918730", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.48550/arXiv.1903.08261", "primary_object": { "basename": "1903.08261.pdf", "url": "https://authors.library.caltech.edu/records/sd3bm-bss62/files/1903.08261.pdf" }, "resource_type": "monograph", "pub_year": "2019", "author_list": "Lee, Nien-En; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/ejkvd-6v976", "eprint_id": 95435, "eprint_status": "archive", "datestamp": "2023-08-19 15:49:18", "lastmod": "2023-10-20 20:13:52", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Unveiling the Origin of Charge Transport in SrTiO_3 Beyond the Quasiparticle Regime", "ispublished": "unpub", "full_text_status": "public", "note": "J.-J.Z. has benefited from discussion with N.-E. Lee. This work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DESC0004993. M.B. acknowledges support by the National Science Foundation under Grant No. ACI-1642443, which provided for code development, and Grant No. CAREER-1750613, which provided for theory and method development. This work was partially supported by the Air Force Office of Scientific Research through the Young Investigator Program, Grant FA9550-18-1-0280. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nSubmitted - 1905.03414.pdf
", "abstract": "In materials with strong electron-phonon (e-ph) interactions, the electrons carry a phonon cloud during their motion, forming quasiparticles known as polarons. Charge transport and its temperature dependence in the polaron regime remain poorly understood. Here, we present first-principles calculations of charge transport in a prototypical material with large polarons, SrTiO_3. Using a cumulant diagram-resummation technique that can capture the strong e-ph interactions, our calculations can accurately predict the experimental electron mobility in SrTiO_3 between 150\u2212300 K. They further reveal that for increasing temperature the charge transport mechanism transitions from band-like conduction, in which the scattering of renormalized quasiparticles is dominant, to an incoherent transport regime governed by dynamical interactions between the electrons and their phonon cloud. Our work reveals long-sought microscopic details of charge transport in SrTiO_3, and provides a broadly applicable method for predicting charge transport in materials with strong e-ph interactions and polarons.", "date": "2019-05-13", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20190513-123336733", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190513-123336733", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.48550/arXiv.1905.03414", "primary_object": { "basename": "1905.03414.pdf", "url": "https://authors.library.caltech.edu/records/ejkvd-6v976/files/1905.03414.pdf" }, "resource_type": "monograph", "pub_year": "2019", "author_list": "Zhou, Jin-Jian and Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/37vnq-w7y82", "eprint_id": 94084, "eprint_status": "archive", "datestamp": "2023-08-19 15:07:41", "lastmod": "2023-10-20 17:39:34", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab initio charge carrier dynamics and its application to materials for energy", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "This talk will discuss novel first-principles calcns. of charge carrier dynamics, which are broadly applicable to materials employed in renewable energy devices. Calcns. of charge transport and ultrafast dynamics have relied on heuristic approaches for the past several decades. Recent progress in combining d. functional theory and related methods with kinetic equations, such as the Boltzmann transport equation (BTE), are enabling spectacular advances in computing carrier dynamics in materials from first principles. A special role is played by the interaction between charge carriers and\nlattice vibrations, also known as the electron-phonon (e-ph) interaction, which dominates carrier dynamics near room temp. and at energies within a few eV of the band gap. We will discuss our recently developed methods to compute e-ph scattering processes from first principles, and show how these developments enable accurate calcns. of charge transport and ultrafast dynamics in materials, including: 1) Accurate calcns. of the electron mobility, leading to new insight into charge transport in polar semiconductors, perovskite oxides, and org. materials. We will also touch briefly on the computation of charge transport in the polaron regime. 2) The ultrafast dynamics of excited (so-called \"hot\") carriers, with application to lighting devices, solar energy conversion, and ultrafast spectroscopy. A new parallel algorithm to propagate in time the BTE for excited electrons and coupled electrons and phonons will be presented. A recent extension to include the elec. field in the BTE and accurately compute velocity-field curves in semiconductors will also be discussed. The talk will close with a discussion of PERTURBO, an open source code we are developing to make these calcns. available to the community.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-081733515", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-081733515", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/efbv0-spd20", "eprint_id": 94083, "eprint_status": "archive", "datestamp": "2023-08-19 15:07:35", "lastmod": "2023-10-20 17:39:29", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Advances in ab initio calculations of light-matter interaction in two-dimensional transition metal dichalcogenides", "ispublished": "unpub", "full_text_status": "restricted", "note": "\u00a9 2019 American Chemical Society.", "abstract": "Two-dimensional (2D) transition metal dichalcogenides (TMDs) exhibit unusual electronic and optical properties. This talk will discuss novel first-principles calcns. of light absorption and emission in 2D-TMDs. First, we will show that visible light absorption per unit thickness in monolayer and few-layer TMDs is 1-2 orders of magnitudes greater than in conventional bulk semiconductors, and discuss application of TMDs to solar energy conversion. We will then introduce a formalism combining the ab initio Bethe-Salpeter equation with Fermi's golden rule to investigate light emission in 2DTMDs. We will show calcns. of the radiative lifetimes as a function of temp. in 2D-TMDs, which are in excellent\nagreement with expt. and provide new microscopic insights into exciton recombination in monolayers and heterobilayers. We will also address the anisotropic photoluminescence seen exptl. upon exciting TMDs with linearly polarized light. We generalize our radiative lifetime calcns. to obtain an equation for light emission as a function of angle and polarization, and show the presence of an inherently anisotropic photoluminescence due to the valley degeneracy of the lowest bright excitons. In closing, we will discuss our recent efforts on computing exciton-phonon interactions from first principles, and how these calcns. allow us to investigate nonequil. exciton dynamics in photoexcited 2D-TMDs.", "date": "2019-04", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20190325-081503026", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190325-081503026", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "resource_type": "conference_item", "pub_year": "2019", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/kbzg9-1ye40", "eprint_id": 94235, "eprint_status": "archive", "datestamp": "2023-08-19 14:33:02", "lastmod": "2023-10-20 17:48:20", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Efficient ab initio calculations of electron-defect scattering and defect-limited carrier mobility", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2019 American Physical Society. \n\n(Received 11 January 2019; published 28 March 2019) \n\nI-T.L. thanks Dr. Luis Agapito, Dr. Davide Sangalli, Vatsal Jhalani, Jin-Soo Park, and Xiao Tong for fruitful discussions. This work was supported by the Air Force Office of Scientific Research through the Young Investigator Program Grant No. FA9550-18-1-0280. J.-J.Z. was supported by the National Science Foundation under Grant No. ACI-1642443, which provided for code development. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevMaterials.3.033804.pdf
Submitted - 1901.03449.pdf
", "abstract": "Electron-defect (e\u2212d) interactions govern charge carrier dynamics at low temperature, where they limit the carrier mobility and give rise to phenomena of broad relevance in condensed matter physics. Ab initio calculations of e\u2212d interactions are still in their infancy, mainly because they require large supercells and computationally expensive workflows. Here we develop an efficient ab initio approach for computing elastic e\u2212d interactions, their associated e\u2212d relaxation times (RTs), and the low-temperature defect-limited carrier mobility. The method is applied to silicon with simple neutral defects, such as vacancies and interstitials. Contrary to conventional wisdom, the computed e\u2212d RTs depend strongly on carrier energy and defect type, and the defect-limited mobility is temperature dependent. These results highlight the shortcomings of widely employed heuristic models of e\u2212d interactions in materials. Our method opens avenues for studying e\u2212d scattering and low-temperature charge transport from first principles.", "date": "2019-03", "date_type": "published", "publication": "Physical Review Materials", "volume": "3", "number": "3", "publisher": "American Physical Society (APS)", "pagerange": "Art. No. 033804", "id_number": "CaltechAUTHORS:20190328-093304967", "issn": "2475-9953", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190328-093304967", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1103/physrevmaterials.3.033804", "primary_object": { "basename": "1901.03449.pdf", "url": "https://authors.library.caltech.edu/records/kbzg9-1ye40/files/1901.03449.pdf" }, "related_objects": [ { "basename": "PhysRevMaterials.3.033804.pdf", "url": "https://authors.library.caltech.edu/records/kbzg9-1ye40/files/PhysRevMaterials.3.033804.pdf" } ], "resource_type": "article", "pub_year": "2019", "author_list": "Lu, I-Te; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/31pc5-jj296", "eprint_id": 91368, "eprint_status": "archive", "datestamp": "2023-08-19 12:52:26", "lastmod": "2023-10-19 22:27:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Hellman-Olle", "name": { "family": "Hellman", "given": "Olle" }, "orcid": "0000-0002-3453-2975" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Electron-Phonon Scattering in the Presence of Soft Modes and Electron Mobility in SrTiO_3 Perovskite from First Principles", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\n(Received 14 June 2018; published 30 November 2018) \n\nThis work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. M.\u2009B. acknowledges support by the National Science Foundation under Grant No. ACI-1642443, which provided for code development, and Grant No. CAREER-1750613, which provided for theory and method development. This work was partially supported by the Air Force Office of Scientific Research through Young Investigator Program Grant No. FA9550-18-1-0280. O.\u2009H. acknowledges support from the EFRI-2DARE program of the National Science Foundation, Award No. 1433467. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevLett.121.226603.pdf
Accepted Version - 1806.05775
Supplemental Material - SI_for_review.pdf
Supplemental Material - supplemental_material.pdf
", "abstract": "Structural phase transitions and soft phonon modes pose a long-standing challenge to computing electron-phonon (e-ph) interactions in strongly anharmonic crystals. Here we develop a first-principles approach to compute e-ph scattering and charge transport in materials with anharmonic lattice dynamics. Our approach employs renormalized phonons to compute the temperature-dependent e-ph coupling for all phonon modes, including the soft modes associated with ferroelectricity and phase transitions. We show that the electron mobility in cubic SrTiO_3 is controlled by scattering with longitudinal optical phonons at room temperature and with ferroelectric soft phonons below 200 K. Our calculations can accurately predict the temperature dependence of the electron mobility in SrTiO_3 between 150\u2013300 K, and reveal the microscopic origin of its roughly T^(\u22123) trend. Our approach enables first-principles calculations of e-ph interactions and charge transport in broad classes of crystals with phase transitions and strongly anharmonic phonons.", "date": "2018-11-30", "date_type": "published", "publication": "Physical Review Letters", "volume": "121", "number": "22", "publisher": "American Physical Society", "pagerange": "Art. No. 226603", "id_number": "CaltechAUTHORS:20181130-125158827", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181130-125158827", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "NSF", "grant_number": "DMR-1750613" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "NSF", "grant_number": "EFMA-1433467" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/physrevlett.121.226603", "primary_object": { "basename": "1806.05775", "url": "https://authors.library.caltech.edu/records/31pc5-jj296/files/1806.05775" }, "related_objects": [ { "basename": "PhysRevLett.121.226603.pdf", "url": "https://authors.library.caltech.edu/records/31pc5-jj296/files/PhysRevLett.121.226603.pdf" }, { "basename": "SI_for_review.pdf", "url": "https://authors.library.caltech.edu/records/31pc5-jj296/files/SI_for_review.pdf" }, { "basename": "supplemental_material.pdf", "url": "https://authors.library.caltech.edu/records/31pc5-jj296/files/supplemental_material.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Zhou, Jin-Jian; Hellman, Olle; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sn7nc-4mq11", "eprint_id": 99471, "eprint_status": "archive", "datestamp": "2023-08-19 11:30:00", "lastmod": "2023-10-18 18:20:07", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Photovoltaics: Advances in First Principles Modeling \u2013 Overview", "ispublished": "unpub", "full_text_status": "public", "note": "\u00a9 2018 Springer Nature Switzerland AG. \n\nFirst Online: 17 September 2018.", "abstract": "Photovoltaic devices are challenging to model due to their multi-scale physics, which ranges from light absorption to charge carrier generation and transport. This overview chapter outlines recent developments in first-principles modeling of solar cells. Besides the traditional focus on predicting the structure, bandgap, and optical properties of materials, first-principles methods can now also model charge transport and excited carrier dynamics. New materials are breaking the established paradigms of conventional solar cells, leading to exciting discoveries of broad relevance to materials science and physics. We discuss three recent directions in photovoltaics research, including ultrathin solar cells, complex materials, and ultrafast electron dynamics, and outline future challenges. First-principles calculations are playing a key role in pushing these frontiers of photovoltaics research.", "date": "2018-09-17", "date_type": "published", "publisher": "Springer", "place_of_pub": "Cham", "pagerange": "1-8", "id_number": "CaltechAUTHORS:20191025-155916732", "isbn": "978-3-319-50257-1", "book_title": "Handbook of Materials Modeling - Applications: Current and Emerging Materials", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191025-155916732", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Andreoni-W", "name": { "family": "Andreoni", "given": "Wanda" } }, { "id": "Yip-Sidney", "name": { "family": "Yip", "given": "Sidney" } } ] }, "doi": "10.1007/978-3-319-50257-1_143-1", "resource_type": "book_section", "pub_year": "2018", "author_list": "Bernardi, Marco and Grossman, Jeffrey C." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/2kxxf-1km94", "eprint_id": 87538, "eprint_status": "archive", "datestamp": "2023-08-19 09:49:42", "lastmod": "2023-10-18 21:15:10", "type": "monograph", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Hellman-Olle", "name": { "family": "Hellman", "given": "Olle" }, "orcid": "0000-0002-3453-2975" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Temperature Dependent Electron-Phonon Scattering and Electron Mobility in SrTiO_3 Perovskite from First Principles", "ispublished": "unpub", "full_text_status": "public", "note": "This work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. de-sc0004993. M.B. acknowledges support by the National Science Foundation under Grant No. ACI-1642443, which provided for basic theory and electron-phonon code development. O.H. acknowledge support from the EFRI-2DARE program of the National Science Foundation, Award No. 1433467. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nSubmitted - 1806.05775.pdf
", "abstract": "Structural phase transitions and soft phonon modes pose a longstanding challenge to computing electron-phonon (e-ph) interactions in strongly anharmonic crystals. Here we develop a first-principles approach to compute e-ph scattering and charge transport in materials with anharmonic lattice dynamics. Our approach employs renormalized phonons to compute the temperature-dependent e-ph coupling for all phonon modes, including the soft modes associated with ferroelectricity and phase transitions. We show that the electron mobility in cubic SrTiO_3 is controlled by scattering with longitudinal optical phonons at room temperature and with ferroelectric soft phonons below 200~K. Our calculations can accurately predict the temperature dependence of the electron mobility between 150\u2212300~K, and reveal the origin of the T^(\u22123) dependence of the electron mobility in SrTiO_3. Our approach enables first-principles calculations of e-ph interactions and charge transport in broad classes of crystals with phase transitions and strongly anharmonic phonons.", "date": "2018-07-05", "date_type": "published", "publisher": "arXiv", "id_number": "CaltechAUTHORS:20180703-140325969", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180703-140325969", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "NSF", "grant_number": "EFMA-1433467" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.48550/arXiv.1806.05775", "primary_object": { "basename": "1806.05775.pdf", "url": "https://authors.library.caltech.edu/records/2kxxf-1km94/files/1806.05775.pdf" }, "resource_type": "monograph", "pub_year": "2018", "author_list": "Zhou, Jin-Jian; Hellman, Olle; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cw3sw-kv213", "eprint_id": 87378, "eprint_status": "archive", "datestamp": "2023-08-19 09:49:30", "lastmod": "2023-10-18 21:07:19", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Agapito-L-A", "name": { "family": "Agapito", "given": "Luis A." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab initio electron-phonon interactions using atomic orbital wave functions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\nReceived 16 March 2018; revised manuscript received 6 June 2018; published 27 June 2018. \n\nL.A. thanks Prof. M. Wierzbowska and Dr. A. Ferretti for technical discussions. This work was supported by the National Science Foundation under Grant No. ACI-1642443. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation Grant No. ACI-1548562. In particular, it used the Comet system at the San Diego Supercomputing Center (SDSC) through allocation DMR150128.\n\nPublished - PhysRevB.97.235146.pdf
Submitted - 1803.06374.pdf
Supplemental Material - Supp-final.pdf
", "abstract": "The interaction between electrons and lattice vibrations determines key physical properties of materials, including their electrical and heat transport, excited electron dynamics, phase transitions, and superconductivity. We present an ab initio method that employs atomic orbital (AO) wave functions to compute the electron-phonon (e-ph) interactions in materials and interpolate the e-ph coupling matrix elements to fine Brillouin zone grids. We detail the numerical implementation of such AO-based e-ph calculations, and benchmark them against direct density functional theory calculations and Wannier function (WF) interpolation. The key advantages of AOs over WFs for e-ph calculations are outlined. Since AOs are fixed basis functions associated with the atoms, they circumvent the need to generate a material-specific localized basis set with a trial-and-error approach, as is needed in WFs. Therefore, AOs are ideal to compute e-ph interactions in chemically and structurally complex materials for which WFs are challenging to generate, and are also promising for high-throughput materials discovery. While our results focus on AOs, the formalism we present generalizes e-ph calculations to arbitrary localized basis sets, with WFs recovered as a special case.", "date": "2018-06-15", "date_type": "published", "publication": "Physical Review B", "volume": "97", "number": "23", "publisher": "American Physical Society", "pagerange": "Art. No. 235146", "id_number": "CaltechAUTHORS:20180627-091913501", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180627-091913501", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "ACI-1548562" }, { "agency": "NSF", "grant_number": "DMR-150128" } ] }, "doi": "10.1103/PhysRevB.97.235146", "primary_object": { "basename": "1803.06374.pdf", "url": "https://authors.library.caltech.edu/records/cw3sw-kv213/files/1803.06374.pdf" }, "related_objects": [ { "basename": "PhysRevB.97.235146.pdf", "url": "https://authors.library.caltech.edu/records/cw3sw-kv213/files/PhysRevB.97.235146.pdf" }, { "basename": "Supp-final.pdf", "url": "https://authors.library.caltech.edu/records/cw3sw-kv213/files/Supp-final.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Agapito, Luis A. and Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/cnj73-k3d04", "eprint_id": 86277, "eprint_status": "archive", "datestamp": "2023-08-19 09:46:50", "lastmod": "2023-10-18 19:25:43", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Chen-Hsiao-Yi", "name": { "family": "Chen", "given": "Hsiao-Yi" }, "orcid": "0000-0003-1962-5767" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Sangalli-Davide", "name": { "family": "Sangalli", "given": "Davide" }, "orcid": "0000-0002-4268-9454" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Theory and Ab Initio Computation of the Anisotropic Light Emission in Monolayer Transition Metal Dichalcogenides", "ispublished": "pub", "full_text_status": "public", "keywords": "Transition metal dichalcogenides, photoluminescence, exciton, first-principles, radiative lifetime, Bethe\u2212Salpeter equation", "note": "\u00a9 2018 American Chemical Society. \n\nReceived: March 20, 2018; Revised: May 5, 2018; Published: May 8, 2018. \n\nH.-Y.C thanks the Taiwan Ministry of Education for fellowship support. M.B. acknowledges support by the National Science Foundation under grant no. ACI-1642443 and partial support from the Space Solar Program Initiative at the California Institute of Technology. M.P. acknowledges PRACE for computational resources on Marconi at CINECA (Grant No. Pra16_4181), and the Tor Vergata University for financial support through the Mission Sustainability Project 2DUTOPI. D.S. acknowledges funding from the European Union project MaX Materials design at the eXascale H2020-EINFRA-2015-1, grant agreement no. 676598, and Nanoscience Foundries and Fine Analysis - Europe H2020-INFRAIA-2014-2015, grant agreement no. 654360. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract no DE-AC02-05CH11231. \n\nThe authors declare no competing financial interest.\n\nSubmitted - 1802.02672.pdf
Supplemental Material - nl8b01114_si_001.pdf
", "abstract": "Monolayer transition metal dichalcogenides (TMDCs) are direct gap semiconductors with a unique potential for use in ultrathin light emitters. However, their photoluminescence (PL) is not completely understood. We develop an approach to compute the radiative recombination rate in monolayer TMDCs as a function of photon emission direction and polarization. Using exciton wavefunctions and energies obtained with the ab initio Bethe\u2212Salpeter equation, we obtain polar plots of the PL for different scenarios. Our results can explain the PL anisotropy and polarization dependence measured in recent experiments and predict that light is emitted with a peak intensity normal to the exciton dipole in monolayer TMDCs. We show that excitons emit light anisotropically upon recombination when they are in any quantum superposition state of the K and K\u2032 inequivalent valleys. When averaged over the emission angle and exciton momentum, our new treatment recovers the temperature-dependent radiative lifetimes that we previously derived. Our work demonstrates a generally applicable first-principles approach to studying anisotropic light emission in two-dimensional materials.", "date": "2018-06-13", "date_type": "published", "publication": "Nano Letters", "volume": "18", "number": "6", "publisher": "American Chemical Society", "pagerange": "3839-3843", "id_number": "CaltechAUTHORS:20180508-101719499", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180508-101719499", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Ministry of Education (Taipei)" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Caltech Space Solar Program Initiative" }, { "agency": "CINECA", "grant_number": "Pra16_4181" }, { "agency": "Tor Vergata University", "grant_number": "2DUTOPI" }, { "agency": "European Research Council (ERC)", "grant_number": "676598" }, { "agency": "European Research Council (ERC)", "grant_number": "654360" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1021/acs.nanolett.8b01114", "primary_object": { "basename": "nl8b01114_si_001.pdf", "url": "https://authors.library.caltech.edu/records/cnj73-k3d04/files/nl8b01114_si_001.pdf" }, "related_objects": [ { "basename": "1802.02672.pdf", "url": "https://authors.library.caltech.edu/records/cnj73-k3d04/files/1802.02672.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Chen, Hsiao-Yi; Palummo, Maurizia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/t31vy-7dm36", "eprint_id": 86280, "eprint_status": "archive", "datestamp": "2023-08-19 09:10:31", "lastmod": "2023-10-18 19:25:55", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Frohna-Kyle", "name": { "family": "Frohna", "given": "Kyle" }, "orcid": "0000-0002-2259-6154" }, { "id": "Deshpande-Tejas", "name": { "family": "Deshpande", "given": "Tejas" }, "orcid": "0000-0003-0326-1372" }, { "id": "Harter-John-W", "name": { "family": "Harter", "given": "John" }, "orcid": "0000-0002-7146-9370" }, { "id": "Peng-Wei", "name": { "family": "Peng", "given": "Wei" } }, { "id": "Barker-Bradford-A", "name": { "family": "Barker", "given": "Bradford A." } }, { "id": "Neaton-Jeffrey-B", "name": { "family": "Neaton", "given": "Jeffrey B." }, "orcid": "0000-0001-7585-6135" }, { "id": "Louie-Steven-G", "name": { "family": "Louie", "given": "Steven G." } }, { "id": "Bakr-Osman-M", "name": { "family": "Bakr", "given": "Osman M." } }, { "id": "Hsieh-David", "name": { "family": "Hsieh", "given": "David" }, "orcid": "0000-0002-0812-955X" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Inversion symmetry and bulk Rashba effect in methylammonium lead iodide perovskite single crystals", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived: 01 December 2017; Accepted: 12 April 2018; Published: 08 May 2018. \n\nM.B. acknowledges partial support from start-up funds and from the Space Solar Program Initiative at the California Institute of Technology. K.F. thanks the California Institute of Technology for support through the SURF fellowship program, and Peter Foley and Linn Leppert for fruitful discussions. SHG-RA measurements were supported by the U. S. Department of Energy under grant DE-SC0010533. D.H. also acknowledges funding for instrumentation from the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center (PHY-1125565) with support of the Gordon and Betty Moore Foundation through grant GBMF1250. O.M.B and W.P. acknowledge the support of KAUST. J.B.N. and S.G.L. were supported by the U.S. Department of Energy, Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract No. DE-AC02-05CH11231, through the Theory FWP (KC2301) at Lawrence Berkeley National Laboratory (LBNL). This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231. \n\nData availability: The authors declare that the data supporting the findings of this study are available within the paper and its Supplementary Information files. \n\nAuthor Contributions: M.B. conceived the project. K.F. and M.B. carried out the calculations and prepared the manuscript with input from co-authors. W.P. and O.B. synthesized and provided the samples. T.D., J.H., and D.H. designed and conducted the experiments. B.B. contributed to the calculations. J.B.N. and S.G.L. contributed to conceive the theory and calculations. All authors edited the manuscript. \n\nThe authors declare no competing interests.\n\nPublished - s41467-018-04212-w.pdf
Supplemental Material - 41467_2018_4212_MOESM1_ESM.pdf
Supplemental Material - 41467_2018_4212_MOESM2_ESM.pdf
Supplemental Material - 41467_2018_4212_MOESM3_ESM.pdf
Supplemental Material - 41467_2018_4212_MOESM4_ESM.cif
Supplemental Material - 41467_2018_4212_MOESM5_ESM.cif
Supplemental Material - 41467_2018_4212_MOESM6_ESM.cif
", "abstract": "Methylammonium lead iodide perovskite (MAPbI_3) exhibits long charge carrier lifetimes that are linked to its high efficiency in solar cells. Yet, the mechanisms governing these unusual carrier dynamics are not completely understood. A leading hypothesis\u2014disproved in this work\u2014is that a large, static bulk Rashba effect slows down carrier recombination. Here, using second harmonic generation rotational anisotropy measurements on MAPbI_3 crystals, we demonstrate that the bulk structure of tetragonal MAPbI_3 is centrosymmetric with I4/mcmspace group. Our calculations show that a significant Rashba splitting in the bandstructure requires a non-centrosymmetric lead iodide framework, and that incorrect structural relaxations are responsible for the previously predicted large Rashba effect. The small Rashba splitting allows us to compute effective masses in excellent agreement with experiment. Our findings rule out the presence of a large static Rashba effect in bulk MAPbI_3, and our measurements find no evidence of dynamic Rashba effects.", "date": "2018-05-08", "date_type": "published", "publication": "Nature Communications", "volume": "9", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 1829", "id_number": "CaltechAUTHORS:20180508-105825258", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180508-105825258", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech Summer Undergraduate Research Fellowship (SURF)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0010533" }, { "agency": "Institute for Quantum Information and Matter (IQIM)" }, { "agency": "NSF", "grant_number": "PHY-1125565" }, { "agency": "Gordon and Betty Moore Foundation", "grant_number": "GBMF1250" }, { "agency": "King Abdullah University of Science and Technology (KAUST)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "Caltech Space Solar Program Initiative" } ] }, "local_group": { "items": [ { "id": "IQIM" } ] }, "doi": "10.1038/s41467-018-04212-w", "pmcid": "PMC5940805", "primary_object": { "basename": "41467_2018_4212_MOESM5_ESM.cif", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/41467_2018_4212_MOESM5_ESM.cif" }, "related_objects": [ { "basename": "41467_2018_4212_MOESM6_ESM.cif", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/41467_2018_4212_MOESM6_ESM.cif" }, { "basename": "s41467-018-04212-w.pdf", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/s41467-018-04212-w.pdf" }, { "basename": "41467_2018_4212_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/41467_2018_4212_MOESM1_ESM.pdf" }, { "basename": "41467_2018_4212_MOESM2_ESM.pdf", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/41467_2018_4212_MOESM2_ESM.pdf" }, { "basename": "41467_2018_4212_MOESM3_ESM.pdf", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/41467_2018_4212_MOESM3_ESM.pdf" }, { "basename": "41467_2018_4212_MOESM4_ESM.cif", "url": "https://authors.library.caltech.edu/records/t31vy-7dm36/files/41467_2018_4212_MOESM4_ESM.cif" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Frohna, Kyle; Deshpande, Tejas; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8tsby-3pm97", "eprint_id": 85387, "eprint_status": "archive", "datestamp": "2023-08-19 08:21:21", "lastmod": "2023-10-18 18:10:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lee-Nien-En", "name": { "family": "Lee", "given": "Nien-En" }, "orcid": "0000-0002-3172-7750" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Agapito-Luis-A", "name": { "family": "Agapito", "given": "Luis A." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2018 American Physical Society. \n\nReceived 1 December 2017; revised manuscript received 9 February 2018; published 16 March 2018. \n\nThe authors thank M. Palummo for discussions. N.-E.L. acknowledges the Physics department at Caltech for the TA Relief Fellowship. M.B. and L.A. acknowledge support by the National Science Foundation under Grant No. ACI-1642443, which provided for basic theory and electron-phonon code development. This work was partially supported by the Young Investigator Program of the Air Force Office of Scientific Research (AFOSR), under Grant FA9550-18-1-0280. J.-J. Zhou was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: The development of the scattering rate and mobility calculations was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.97.115203.pdf
Accepted Version - 1712.00490.pdf
", "abstract": "Predicting charge transport in organic molecular crystals is notoriously challenging. Carrier mobility calculations in organic semiconductors are dominated by quantum chemistry methods based on charge hopping, which are laborious and only moderately accurate. We compute from first principles the electron-phonon scattering and the phonon-limited hole mobility of naphthalene crystal in the framework of ab initio band theory. Our calculations combine GW electronic bandstructures, ab initio electron-phonon scattering, and the Boltzmann transport equation. The calculated hole mobility is in very good agreement with experiment between 100 \u2013 300 K, and we can predict its temperature dependence with high accuracy. We show that scattering between intermolecular phonons and holes regulates the mobility, though intramolecular phonons possess the strongest coupling with holes. We revisit the common belief that only rigid molecular motions affect carrier dynamics in organic molecular crystals. Our paper provides a quantitative and rigorous framework to compute charge transport in organic crystals and is a first step toward reconciling band theory and carrier hopping computational methods.", "date": "2018-03-15", "date_type": "published", "publication": "Physical Review B", "volume": "97", "number": "11", "publisher": "American Physical Society", "pagerange": "Art. No. 115203", "id_number": "CaltechAUTHORS:20180321-075518336", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180321-075518336", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-18-1-0280" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/PhysRevB.97.115203", "primary_object": { "basename": "PhysRevB.97.115203.pdf", "url": "https://authors.library.caltech.edu/records/8tsby-3pm97/files/PhysRevB.97.115203.pdf" }, "related_objects": [ { "basename": "1712.00490.pdf", "url": "https://authors.library.caltech.edu/records/8tsby-3pm97/files/1712.00490.pdf" } ], "resource_type": "article", "pub_year": "2018", "author_list": "Lee, Nien-En; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/syh64-cbm50", "eprint_id": 78766, "eprint_status": "archive", "datestamp": "2023-08-19 04:37:24", "lastmod": "2023-10-26 00:22:22", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Jhalani-V-A", "name": { "family": "Jhalani", "given": "Vatsal A." }, "orcid": "0000-0003-0866-0858" }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ultrafast Hot Carrier Dynamics in GaN and its Impact on the Efficiency Droop", "ispublished": "pub", "full_text_status": "public", "keywords": "Gallium nitride, light emitting diodes, ultrafast dynamics, electron-phonon scattering", "note": "\u00a9 2017 American Chemical Society. \n\nReceived: May 25, 2017; Revised: July 20, 2017; Published: July 24, 2017. \n\nV.J. thanks the Resnick Sustainibility Institute at Caltech for fellowship support. J.-J.Z. acknowledges support from the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: the development of the computational methods employed in this work was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. M.B. acknowledges support by the National Science Foundation under Grant No. ACI-1642443, which provided for basic theory and part of the electronphonon coupling code development. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The authors thank Davide Sangalli for fruitful discussions. \n\nAuthor Contributions: M.B. conceived and designed the research. V.J. and J.-J.Z. developed the computational codes and carried out the calculations. All authors wrote the manuscript. \n\nThe authors declare no competing financial interest.\n\nAccepted Version - acs.nanolett.7b02212_acc.pdf
Submitted - 1703.07880.pdf
Supplemental Material - nl7b02212_si_001.pdf
", "abstract": "GaN is a key material for lighting technology. Yet, the carrier transport and ultrafast dynamics that are central in GaN light-emitting devices are not completely understood. We present first-principles calculations of carrier dynamics in GaN, focusing on electron\u2013phonon (e-ph) scattering and the cooling and nanoscale dynamics of hot carriers. We find that e-ph scattering is significantly faster for holes compared to electrons and that for hot carriers with an initial 0.5\u20131 eV excess energy, holes take a significantly shorter time (\u223c0.1 ps) to relax to the band edge compared to electrons, which take \u223c1 ps. The asymmetry in the hot carrier dynamics is shown to originate from the valence band degeneracy, the heavier effective mass of holes compared to electrons, and the details of the coupling to different phonon modes in the valence and conduction bands. We show that the slow cooling of hot electrons and their long ballistic mean free paths (over 3 nm at room temperature) are a possible cause of efficiency droop in GaN light-emitting diodes. Taken together, our work sheds light on the ultrafast dynamics of hot carriers in GaN and the nanoscale origin of efficiency droop.", "date": "2017-08-09", "date_type": "published", "publication": "Nano Letters", "volume": "17", "number": "8", "publisher": "American Chemical Society", "pagerange": "5012-5019", "id_number": "CaltechAUTHORS:20170705-124137567", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170705-124137567", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Resnick Sustainability Institute" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "NSF", "grant_number": "ACI-1642443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" }, { "id": "Resnick-Sustainability-Institute" } ] }, "doi": "10.1021/acs.nanolett.7b02212", "primary_object": { "basename": "1703.07880.pdf", "url": "https://authors.library.caltech.edu/records/syh64-cbm50/files/1703.07880.pdf" }, "related_objects": [ { "basename": "acs.nanolett.7b02212_acc.pdf", "url": "https://authors.library.caltech.edu/records/syh64-cbm50/files/acs.nanolett.7b02212_acc.pdf" }, { "basename": "nl7b02212_si_001.pdf", "url": "https://authors.library.caltech.edu/records/syh64-cbm50/files/nl7b02212_si_001.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Jhalani, Vatsal A.; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qtf70-nsq39", "eprint_id": 78249, "eprint_status": "archive", "datestamp": "2023-08-19 03:38:28", "lastmod": "2023-10-25 23:55:23", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Lu-I-Te", "name": { "family": "Lu", "given": "I-Te" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Using defects to store energy in materials \u2013 a computational study", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived: 21 November 2016; Accepted: 28 March 2017; Published online: 13 June 2017. \n\nThe authors acknowledge fruitful discussions with Prof. Brent Fultz and Prof. William Johnson. M.B. thanks the California Institute of Technology for start-up funds. I.L. acknowledges partial support through the Government Scholarship for USA Study by the Ministry of Education of Taiwan. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US Department of Energy under Contract No. DE-AC02-05CH11231. \n\nAuthor Contributions: All authors contributed equally and reviewed the manuscript. \n\nThe authors declare that they have no competing interests.\n\nPublished - art_3A10.1038_2Fs41598-017-01434-8.pdf
Supplemental Material - 41598_2017_1434_MOESM1_ESM.pdf
", "abstract": "Energy storage occurs in a variety of physical and chemical processes. In particular, defects in materials can be regarded as energy storage units since they are long-lived and require energy to be formed. Here, we investigate energy storage in non-equilibrium populations of materials defects, such as those generated by bombardment or irradiation. We first estimate upper limits and trends for energy storage using defects. First-principles calculations are then employed to compute the stored energy in the most promising elemental materials, including tungsten, silicon, graphite, diamond and graphene, for point defects such as vacancies, interstitials and Frenkel pairs. We find that defect concentrations achievable experimentally (~0.1\u20131\u2009at.%) can store large energies per volume and weight, up to ~5\u2009MJ/L and 1.5\u2009MJ/kg for covalent materials. Engineering challenges and proof-of-concept devices for storing and releasing energy with defects are discussed. Our work demonstrates the potential of storing energy using defects in materials.", "date": "2017-06-13", "date_type": "published", "publication": "Scientific Reports", "volume": "7", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 3403", "id_number": "CaltechAUTHORS:20170615-104758857", "issn": "2045-2322", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170615-104758857", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "Ministry of Education (Taipei)" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1038/s41598-017-01434-8", "pmcid": "PMC5469865", "primary_object": { "basename": "41598_2017_1434_MOESM1_ESM.pdf", "url": "https://authors.library.caltech.edu/records/qtf70-nsq39/files/41598_2017_1434_MOESM1_ESM.pdf" }, "related_objects": [ { "basename": "art_3A10.1038_2Fs41598-017-01434-8.pdf", "url": "https://authors.library.caltech.edu/records/qtf70-nsq39/files/art_3A10.1038_2Fs41598-017-01434-8.pdf" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Lu, I-Te and Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fh4hn-d2a53", "eprint_id": 77441, "eprint_status": "archive", "datestamp": "2023-08-19 03:07:02", "lastmod": "2023-10-25 23:02:54", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Najafi-Ebrahim", "name": { "family": "Najafi", "given": "Ebrahim" }, "orcid": "0000-0003-3634-9346" }, { "id": "Ivanov-Vsevolod", "name": { "family": "Ivanov", "given": "Vsevolod" } }, { "id": "Zewail-A-H", "name": { "family": "Zewail", "given": "Ahmed" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Super-diffusion of excited carriers in semiconductors", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 The Author(s). This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. \n\nReceived: 01 July 2016; Accepted: 03 March 2017; Published online: 11 May 2017. \n\nThis work was supported by NSF grant DMR-0964886 and Air Force Office of Scientific Research grant FA9550-11-1-0055 in the Physical Biology Center for Ultrafast Science and Technology at California Institute of Technology, which is supported by the Gordon and Betty Moore Foundation. M.B. thanks the California Institute of Technology for a start-up fund. V.I. and M.B. gratefully acknowledge support by the Caltech-GIST program. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. \n\nAuthor Contributions: E.N. and A.Z. conceived and designed the experiments. E.N. carried out the experiments and analysed the data. V.I. and M.B. developed the theory and carried out numerical simulations and ab initio calculations. E.N. and M.B. wrote the manuscript. All authors reviewed the manuscript. \n\nThe authors declare no competing financial interests.\n\nPublished - ncomms15177.pdf
Supplemental Material - ncomms15177-s1.pdf
Supplemental Material - ncomms15177-s2.mov
Supplemental Material - ncomms15177-s3.mov
Supplemental Material - ncomms15177-s4.pdf
", "abstract": "The ultrafast spatial and temporal dynamics of excited carriers are important to understanding the response of materials to laser pulses. Here we use scanning ultrafast electron microscopy to image the dynamics of electrons and holes in silicon after excitation with a short laser pulse. We find that the carriers exhibit a diffusive dynamics at times shorter than 200\u2009ps, with a transient diffusivity up to 1,000 times higher than the room temperature value, D_0\u224830\u2009cm^2 s^(\u22121). The diffusivity then decreases rapidly, reaching a value of D_0 roughly 500\u2009ps after the excitation pulse. We attribute the transient super-diffusive behaviour to the rapid expansion of the excited carrier gas, which equilibrates with the environment in 100\u2212150\u2009ps. Numerical solution of the diffusion equation, as well as ab initio calculations, support our interpretation. Our findings provide new insight into the ultrafast spatial dynamics of excited carriers in materials.", "date": "2017-05-11", "date_type": "published", "publication": "Nature Communications", "volume": "8", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 15177", "id_number": "CaltechAUTHORS:20170515-091501991", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170515-091501991", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "DMR-0964886" }, { "agency": "Air Force Office of Scientific Research (AFOSR)", "grant_number": "FA9550-11-1-0055" }, { "agency": "Gordon and Betty Moore Foundation" }, { "agency": "Caltech-GIST Program" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1038/ncomms15177", "pmcid": "PMC5437287", "primary_object": { "basename": "ncomms15177-s4.pdf", "url": "https://authors.library.caltech.edu/records/fh4hn-d2a53/files/ncomms15177-s4.pdf" }, "related_objects": [ { "basename": "ncomms15177.pdf", "url": "https://authors.library.caltech.edu/records/fh4hn-d2a53/files/ncomms15177.pdf" }, { "basename": "ncomms15177-s1.pdf", "url": "https://authors.library.caltech.edu/records/fh4hn-d2a53/files/ncomms15177-s1.pdf" }, { "basename": "ncomms15177-s2.mov", "url": "https://authors.library.caltech.edu/records/fh4hn-d2a53/files/ncomms15177-s2.mov" }, { "basename": "ncomms15177-s3.mov", "url": "https://authors.library.caltech.edu/records/fh4hn-d2a53/files/ncomms15177-s3.mov" } ], "resource_type": "article", "pub_year": "2017", "author_list": "Najafi, Ebrahim; Ivanov, Vsevolod; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zbfvj-jb128", "eprint_id": 77203, "eprint_status": "archive", "datestamp": "2023-08-19 01:48:28", "lastmod": "2023-10-25 21:58:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Ataca-Can", "name": { "family": "Ataca", "given": "Can" } }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Grossman-Jeffrey-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Optical and Electronic Properties of Two-Dimensional Layered Materials", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2017 M. Bernardi et al., published by De Gruyter Open.\nThis work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License. \n\nReceived May 9, 2015; accepted December 1, 2015. \n\nM.B. acknowledges support by a start-up fund from the California Institute of Technology. M.P. acknowledges E.C. for the RISE Project CoExAN GA644076. J.C.G. and C.A. are grateful to the Eni Solar Frontiers Center for financial support.\n\nPublished - _Nanophotonics__Optical_and_Electronic_Properties_of_Two-Dimensional_Layered_Materials.pdf
", "abstract": "Modern semiconductor devices have revolutionized wide-ranging technologies such as electronics, lighting, solar\nenergy, and communication [1]. The semiconductor industry\nemploys Si to fabricate electronic circuits, and GaAs,\nGaN, and other III\u2013V materials for optoelectronics [2], with\ntypical substrates consisting of wafers manufactured at\nhigh temperature. Precisely controlled thin films can be\ndeposited on the substrate to achieve additional functionality, for example by chemical vapor deposition (CVD) or molecular beam epitaxy [3].", "date": "2017-03", "date_type": "published", "publication": "Nanophotonics", "volume": "6", "number": "2", "publisher": "De Gruyter", "pagerange": "479-493", "id_number": "CaltechAUTHORS:20170505-080500572", "issn": "2192-8606", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170505-080500572", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "European Research Council (ERC)", "grant_number": "CoExAN GA644076" }, { "agency": "Eni Solar Frontiers Center" } ] }, "collection": "CaltechAUTHORS", "doi": "10.1515/nanoph-2015-0030", "primary_object": { "basename": "_Nanophotonics__Optical_and_Electronic_Properties_of_Two-Dimensional_Layered_Materials.pdf", "url": "https://authors.library.caltech.edu/records/zbfvj-jb128/files/_Nanophotonics__Optical_and_Electronic_Properties_of_Two-Dimensional_Layered_Materials.pdf" }, "resource_type": "article", "pub_year": "2017", "author_list": "Bernardi, Marco; Ataca, Can; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/v3h2x-fjf61", "eprint_id": 99541, "eprint_status": "archive", "datestamp": "2023-08-19 00:43:35", "lastmod": "2023-10-18 18:32:43", "type": "conference_item", "metadata_visibility": "show", "creators": { "items": [ { "id": "Agapito-L-A", "name": { "family": "Agapito", "given": "Luis" } }, { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Jhalani-V-A", "name": { "family": "Jhalani", "given": "Vatsal" }, "orcid": "0000-0003-0866-0858" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "PERTURBO: A software platform for accelerated discovery of\n microscopic processes in materials", "ispublished": "unpub", "full_text_status": "public", "note": "Published - 2017_nsf_see_poster_high.pdf
", "abstract": "Solid-state technologies depend crucially on charge\ncarrier scattering and dynamics. Charge carriers are\nscattered by quasiparticles and excitations in materials\n(e.g. phonons, defects, photons, electrons, holes, etc.)\n\nPERTURBO is a robust platform to study these\nelectron scattering processes using first-principles\ncalculations and many-body perturbation theory.\nPERTURBO fills a void in the software ecosystem to\ndesign advanced materials, and will foster scientific\nand technological innovation.\n\nPERTURBO combines new computational methods\ndeveloped in our group. The code implementation\nadopts modern programming practices (HDF5,\nversion control, MPI/OpenMP) and will be distributed\nunder the standard open GPL license.", "date": "2017", "date_type": "published", "publisher": "Caltech Library", "id_number": "CaltechAUTHORS:20191029-132109124", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20191029-132109124", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF" }, { "agency": "Natural Sciences and Engineering Research Council of Canada (NSERC)" } ] }, "collection": "CaltechAUTHORS", "primary_object": { "basename": "2017_nsf_see_poster_high.pdf", "url": "https://authors.library.caltech.edu/records/v3h2x-fjf61/files/2017_nsf_see_poster_high.pdf" }, "resource_type": "conference_item", "pub_year": "2017", "author_list": "Agapito, Luis; Zhou, Jin-Jian; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7sf03-5sk77", "eprint_id": 72314, "eprint_status": "archive", "datestamp": "2023-08-19 00:03:51", "lastmod": "2023-10-23 21:37:58", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Zhou-Jin-Jian", "name": { "family": "Zhou", "given": "Jin-Jian" }, "orcid": "0000-0002-1182-9186" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "Ab initio electron mobility and polar phonon scattering in GaAs", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Physical Society. \n\n(Received 10 August 2016; revised manuscript received 18 October 2016; published 28 November 2016) \n\nThis work was supported by the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.\n\nPublished - PhysRevB.94.201201.pdf
Submitted - 1608.03514.pdf
Supplemental Material - supplemental_materials.pdf
", "abstract": "In polar semiconductors and oxides, the long-range nature of the electron-phonon (e\u2212ph) interaction is a bottleneck to compute charge transport from first principles. Here, we develop an efficient ab initio scheme to compute and converge the e\u2212ph relaxation times (RTs) and electron mobility in polar materials. We apply our approach to GaAs, where by using the Boltzmann equation with state-dependent RTs, we compute mobilities in excellent agreement with experiment at 250\u2013500K. The e\u2212ph RTs and the phonon contributions to intravalley and intervalley e\u2212ph scattering are also analyzed. Our work enables efficient ab initio computations of transport and carrier dynamics in polar materials.", "date": "2016-11-15", "date_type": "published", "publication": "Physical Review B", "volume": "94", "number": "20", "publisher": "American Physical Society", "pagerange": "Art. No. 201201(R)", "id_number": "CaltechAUTHORS:20161128-120519486", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161128-120519486", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1103/PhysRevB.94.201201", "primary_object": { "basename": "1608.03514.pdf", "url": "https://authors.library.caltech.edu/records/7sf03-5sk77/files/1608.03514.pdf" }, "related_objects": [ { "basename": "PhysRevB.94.201201.pdf", "url": "https://authors.library.caltech.edu/records/7sf03-5sk77/files/PhysRevB.94.201201.pdf" }, { "basename": "supplemental_materials.pdf", "url": "https://authors.library.caltech.edu/records/7sf03-5sk77/files/supplemental_materials.pdf" } ], "resource_type": "article", "pub_year": "2016", "author_list": "Zhou, Jin-Jian and Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/5y2mx-ktn52", "eprint_id": 71449, "eprint_status": "archive", "datestamp": "2023-08-20 14:19:38", "lastmod": "2023-10-23 15:46:48", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" } ] }, "title": "First-principles dynamics of electrons and phonons", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg. \n\nReceived 27 June 2016; Received in final form 3 September 2016; Published online 2 November 2016. \n\nThe author thanks Jamal Mustafa, Luis Agapito, and Jin-Jian Zhou for fruitful discussions, and Davide Sangalli, Vatsal Jhalani, Nien-En Lee, Bolin Liao, and Celene Barrera for feedback on the manuscript. This work was supported by a start-up fund from the California Institute of Technology.\n\nSubmitted - 1607.00080v1.pdf
", "abstract": "First-principles calculations combining density functional theory and many-body perturbation theory can provide microscopic insight into the dynamics of electrons and phonons in materials. We review this theoretical and computational framework, focusing on perturbative treatments of scattering, dynamics, and transport of electrons and phonons. Application of these first-principles calculations in electronics, lighting, spectroscopy, and renewable energy are discussed.", "date": "2016-11", "date_type": "published", "publication": "European Physical Journal B", "volume": "89", "publisher": "Springer", "pagerange": "Art. No. 239", "id_number": "CaltechAUTHORS:20161025-114155978", "issn": "1434-6028", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161025-114155978", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" } ] }, "doi": "10.1140/epjb/e2016-70399-4", "primary_object": { "basename": "1607.00080v1.pdf", "url": "https://authors.library.caltech.edu/records/5y2mx-ktn52/files/1607.00080v1.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Bernardi, Marco" }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/dhvws-bwz42", "eprint_id": 71734, "eprint_status": "archive", "datestamp": "2023-08-20 14:13:39", "lastmod": "2023-10-23 17:01:37", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Mustafa-J-I", "name": { "family": "Mustafa", "given": "Jamal I." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Neaton-J-B", "name": { "family": "Neaton", "given": "Jeffrey B." }, "orcid": "0000-0001-7585-6135" }, { "id": "Louie-S-G", "name": { "family": "Louie", "given": "Steven G." } } ] }, "title": "Ab initio electronic relaxation times and transport in noble metals", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 American Physical Society.\n\nReceived 24 December 2015; published 5 October 2016.\n\nThis research was supported by the Theory of Materials Program at the Lawrence Berkeley National Laboratory through the Office of Basic Energy Sciences, U.S. Department of Energy, under Contract No. DE-AC02-05CH11231, which provided the GW calculations and scattering rate simulations, and by the National Science Foundation under Grant No. DMR-1508412, which provided for basic theory and electron-phonon coupling matrix element calculations. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, and by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. \n\nJ.I.M. and M.B. contributed equally to this work.\n\nPublished - PhysRevB.94.155105.pdf
", "abstract": "Relaxation times employed to study electron transport in metals are typically taken to be constants and obtained empirically. Here, we use fully ab initio calculations to compute the electron-phonon relaxation times of Cu, Ag, and Au and find that they vary significantly on the Fermi surface, with values from \u223c15 to 45 fs that are correlated with the Fermi surface topology. We compute room-temperature resistivities in excellent agreement with experiment by combining GW quasiparticle band structures, Wannier-interpolated band velocities, and ab initio relaxation times. We introduce an importance sampling scheme to speed up the convergence of resistivity and transport calculations.", "date": "2016-10-15", "date_type": "published", "publication": "Physical Review B", "volume": "94", "number": "15", "publisher": "American Physical Society", "pagerange": "Art. No. 155105", "id_number": "CaltechAUTHORS:20161104-090153350", "issn": "2469-9950", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161104-090153350", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "DMR-1508412" } ] }, "doi": "10.1103/PhysRevB.94.155105", "primary_object": { "basename": "PhysRevB.94.155105.pdf", "url": "https://authors.library.caltech.edu/records/dhvws-bwz42/files/PhysRevB.94.155105.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Mustafa, Jamal I.; Bernardi, Marco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/yrxca-a0n49", "eprint_id": 68751, "eprint_status": "archive", "datestamp": "2023-08-20 12:33:35", "lastmod": "2023-10-19 23:36:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Computer calculations across time and length scales in photovoltaic solar cells", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2016 The Royal Society of Chemistry. \n\nReceived 06 Apr 2016, Accepted 05 May 2016, First published online 05 May 2016. \n\nMB thanks the California Institute of Technology for start-up funds and NERSC for computational resources. MB acknowledges partial support from the Joint Center for Artificial Photosynthesis, a DOE Energy Innovation Hub, as follows: the development of part of this review article was supported through the Office of Science of the U.S. Department of Energy under Award No. DE-SC0004993. JCG is grateful for support from the Eni Solar Frontiers Program at MIT.\n\nPublished - c6ee01010e.pdf
", "abstract": "Photovoltaic (PV) solar cells convert solar energy to electricity through a cascade of microscopic processes spanning over 10 order of magnitudes of time and length. PV conversion involves a complex interplay of photons, charge carriers, and excited states. Processes following light absorption include generation of charge carriers or excitons, exciton dissociation over nanometer lengths and subpicosecond times, and carrier transport over ns\u2013ms times and nm\u2013mm lengths. Computer calculations have become an indispensable tool to understand and engineer solar cells across length and time scales. In this article, we examine the microscopic processes underlying PV conversion and review state-of-the-art computational methods to study PV solar cells. Recent developments and future research challenges are outlined.", "date": "2016-07", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "9", "number": "7", "publisher": "Royal Society of Chemistry", "pagerange": "2197-2218", "id_number": "CaltechAUTHORS:20160629-122500821", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160629-122500821", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Caltech" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0004993" }, { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "Joint Center for Artificial Photosynthesis (JCAP)" } ] }, "local_group": { "items": [ { "id": "JCAP" } ] }, "doi": "10.1039/C6EE01010E", "primary_object": { "basename": "c6ee01010e.pdf", "url": "https://authors.library.caltech.edu/records/yrxca-a0n49/files/c6ee01010e.pdf" }, "resource_type": "article", "pub_year": "2016", "author_list": "Bernardi, Marco and Grossman, Jeffrey C." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zk7nz-hrt98", "eprint_id": 60441, "eprint_status": "archive", "datestamp": "2023-09-15 05:07:23", "lastmod": "2023-10-23 21:13:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Mustafa-J-I", "name": { "family": "Mustafa", "given": "Jamal I." } }, { "id": "Neaton-J-B", "name": { "family": "Neaton", "given": "Jeffrey B." }, "orcid": "0000-0001-7585-6135" }, { "id": "Louie-S-G", "name": { "family": "Louie", "given": "Steven G." } } ] }, "title": "Theory and computation of hot carriers generated by surface plasmon polaritons in noble metals", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2015 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. \n\nReceived 06 January 2015; Accepted 26 March 2015; Published 02 June 2015. \n\nThis research was supported by the SciDAC Program on Excited State Phenomena in Energy Materials funded by the US Department of Energy, Office of Basic Energy Sciences and by the Advanced Scientific Computing Research, under Contract No. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory which provided for algorithm and code developments and simulations; and by the National Science Foundation under grant DMR 10-1006184 which provided for basic theory and formalism. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences and by the the US Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the US Department of Energy. \n\nThese authors contributed equally to this work: Marco Bernardi & Jamal Mustafa.\n\nPublished - ncomms8044.pdf
", "abstract": "Hot carriers (HC) generated by surface plasmon polaritons (SPPs) in noble metals are promising for application in optoelectronics, plasmonics and renewable energy. However, existing models fail to explain key quantitative details of SPP-to-HC conversion experiments. Here we develop a quantum mechanical framework and apply first-principles calculations to study the energy distribution and scattering processes of HCs generated by SPPs in Au and Ag. We find that the relative positions of the s and d bands of noble metals regulate the energy distribution and mean free path of the HCs, and that the electron\u2013phonon interaction controls HC energy loss and transport. Our results prescribe optimal conditions for HC generation and extraction, and invalidate previously employed free-electron-like models. Our work combines density functional theory, GW and electron\u2013phonon calculations to provide microscopic insight into HC generation and ultrafast dynamics in noble metals.", "date": "2015-06", "date_type": "published", "publication": "Nature Communications", "volume": "6", "number": "6", "publisher": "Nature Publishing Group", "pagerange": "Art. No. 7044", "id_number": "CaltechAUTHORS:20150923-131953401", "issn": "2041-1723", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-131953401", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "DMR 10-1006184" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" } ] }, "doi": "10.1038/ncomms8044", "pmcid": "PMC4458868", "primary_object": { "basename": "ncomms8044.pdf", "url": "https://authors.library.caltech.edu/records/zk7nz-hrt98/files/ncomms8044.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Bernardi, Marco; Mustafa, Jamal I.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/gns63-5rh48", "eprint_id": 60450, "eprint_status": "archive", "datestamp": "2023-08-22 15:34:13", "lastmod": "2023-10-24 16:34:24", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Exciton Radiative Lifetimes in Two-Dimensional Transition Metal Dichalcogenides", "ispublished": "pub", "full_text_status": "public", "keywords": "Monolayer materials; transition metal dichalcogenides; luminescence; radiative lifetime; excitons; optoelectronics", "note": "\u00a9 2015 American Chemical Society. \n\nReceived: October 2, 2014; Revised: February 18, 2015; Published: March 23, 2015. \n\nM.P. thanks M. Fanfoni for discussion and D. Varsano and D. Sangalli for help with code implementation. M.B. and J.C.G. thank NERSC and XSEDE for computational resources. M.P. thanks Cineca, within the ISCRA-C initiative, for computational resources. This work was partially supported by the Lockheed Martin Corporation. \n\nM.P. and M.B. contributed equally to this work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl503799t_si_001.pdf
", "abstract": "Light emission in two-dimensional (2D) transition metal dichalcogenides (TMDs) changes significantly with the number of layers and stacking sequence. While the electronic structure and optical absorption are well understood in 2D-TMDs, much less is known about exciton dynamics and radiative recombination. Here, we show first-principles calculations of intrinsic exciton radiative lifetimes at low temperature (4 K) and room temperature (300 K) in TMD monolayers with the chemical formula MX_2 (X = Mo, W, and X = S, Se), as well as in bilayer and bulk MoS2 and in two MX_2 heterobilayers. Our results elucidate the time scale and microscopic origin of light emission in TMDs. We find radiative lifetimes of a few picoseconds at low temperature and a few nanoseconds at room temperature in the monolayers and slower radiative recombination in bulk and bilayer than in monolayer MoS_2. The MoS_2/WS_2 and MoSe_2/WSe_2 heterobilayers exhibit very long-lived (\u223c20\u201330 ns at room temperature) interlayer excitons constituted by electrons localized on the Mo-based and holes on the W-based monolayer. The wide radiative lifetime tunability, together with the ability shown here to predict radiative lifetimes from computations, hold unique potential to manipulate excitons in TMDs and their heterostructures for application in optoelectronics and solar energy conversion.", "date": "2015-05-13", "date_type": "published", "publication": "Nano Letters", "volume": "15", "number": "5", "publisher": "American Chemical Society", "pagerange": "2794-2800", "id_number": "CaltechAUTHORS:20150923-143833542", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-143833542", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "XSEDE" }, { "agency": "Lockheed Martin Corporation" } ] }, "doi": "10.1021/nl503799t", "primary_object": { "basename": "nl503799t_si_001.pdf", "url": "https://authors.library.caltech.edu/records/gns63-5rh48/files/nl503799t_si_001.pdf" }, "resource_type": "article", "pub_year": "2015", "author_list": "Palummo, Maurizia; Bernardi, Marco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y0qbn-4eh22", "eprint_id": 60442, "eprint_status": "archive", "datestamp": "2023-08-22 15:24:29", "lastmod": "2023-10-24 16:33:47", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Vigil-Fowler-Derek", "name": { "family": "Vigil-Fowler", "given": "Derek" } }, { "id": "Ong-Chin-Shen", "name": { "family": "Ong", "given": "Chin Shen" } }, { "id": "Neaton-J-B", "name": { "family": "Neaton", "given": "Jeffrey B." }, "orcid": "0000-0001-7585-6135" }, { "id": "Louie-S-G", "name": { "family": "Louie", "given": "Steven G." } } ] }, "title": "Ab initio study of hot electrons in GaAs", "ispublished": "pub", "full_text_status": "public", "keywords": "hot carriers; semiconductors; GaAs; ultrafast; electron\u2013phonon\nscattering", "note": "\u00a9 2015 National Academy of Sciences.\n\nEdited by Allan H. MacDonald, The University of Texas at Austin, Austin, TX, and approved March 16, 2015 (received for review October 9, 2014). Published ahead of print April 13, 2015.\n\nThis research was supported by the Scientific Discovery through Advanced Computing (SciDAC) Program on Excited State Phenomena in Energy Materials funded by US Department of Energy, Offices of Basic Energy Sciences and Advanced Scientific Computing Research Contract DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory, which provided for algorithm and code developments and simulations, and National Science Foundation Grant DMR 10-1006184, which provided for basic theory and formalism. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, US Department of Energy Contract DE-AC02-05CH11231. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science, US Department of Energy. \n\nAuthor contributions: M.B., D.V.-F., J.B.N., and S.G.L. designed research; M.B., D.V.-F., and C.S.O. performed calculations; M.B., D.V.-F., J.B.N., and S.G.L. analyzed data; M.B., D.V.-F., J.B.N., and S.G.L. wrote the paper; and C.S.O. contributed to code development. \n\nThe authors declare no conflict of interest. \n\nThis article is a PNAS Direct Submission. \n\nThis article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1419446112/-/DCSupplemental.\n\nPublished - PNAS-2015-Bernardi-5291-6.pdf
Supplemental Material - pnas.201419446SI.pdf
", "abstract": "Hot carrier dynamics critically impacts the performance of electronic, optoelectronic, photovoltaic, and plasmonic devices. Hot carriers lose energy over nanometer lengths and picosecond timescales and thus are challenging to study experimentally, whereas calculations of hot carrier dynamics are cumbersome and dominated by empirical approaches. In this work, we present ab initio calculations of hot electrons in gallium arsenide (GaAs) using density functional theory and many-body perturbation theory. Our computed electron\u2013phonon relaxation times at the onset of the \u0393, L, and X valleys are in excellent agreement with ultrafast optical experiments and show that the ultrafast (tens of femtoseconds) hot electron decay times observed experimentally arise from electron\u2013phonon scattering. This result is an important advance to resolve a controversy on hot electron cooling in GaAs. We further find that, contrary to common notions, all optical and acoustic modes contribute substantially to electron\u2013phonon scattering, with a dominant contribution from transverse acoustic modes. This work provides definitive microscopic insight into hot electrons in GaAs and enables accurate ab initio computation of hot carriers in advanced materials.", "date": "2015-04-28", "date_type": "published", "publication": "Proceedings of the National Academy of Sciences of the United States of America", "volume": "112", "number": "17", "publisher": "National Academy of Sciences", "pagerange": "5291-5296", "id_number": "CaltechAUTHORS:20150923-133149273", "issn": "0027-8424", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-133149273", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "DMR 10-1006184" } ] }, "doi": "10.1073/pnas.1419446112", "pmcid": "PMC4418885", "primary_object": { "basename": "pnas.201419446SI.pdf", "url": "https://authors.library.caltech.edu/records/y0qbn-4eh22/files/pnas.201419446SI.pdf" }, "related_objects": [ { "basename": "PNAS-2015-Bernardi-5291-6.pdf", "url": "https://authors.library.caltech.edu/records/y0qbn-4eh22/files/PNAS-2015-Bernardi-5291-6.pdf" } ], "resource_type": "article", "pub_year": "2015", "author_list": "Bernardi, Marco; Vigil-Fowler, Derek; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/f0rkv-6cj63", "eprint_id": 60449, "eprint_status": "archive", "datestamp": "2023-08-22 13:39:25", "lastmod": "2023-10-24 16:34:21", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Gong-Maogang", "name": { "family": "Gong", "given": "Maogang" } }, { "id": "Shastry-Tejas-A", "name": { "family": "Shastry", "given": "Tejas A." } }, { "id": "Xie-Yu", "name": { "family": "Xie", "given": "Yu" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Jasion-Daniel", "name": { "family": "Jasion", "given": "Daniel" } }, { "id": "Luck-Kyle-A", "name": { "family": "Luck", "given": "Kyle A." } }, { "id": "Marks-Tobin-J", "name": { "family": "Marks", "given": "Tobin J." } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" }, { "id": "Ren-Shenqiang", "name": { "family": "Ren", "given": "Shenqiang" } }, { "id": "Hersam-Mark-C", "name": { "family": "Hersam", "given": "Mark C." } } ] }, "title": "Polychiral Semiconducting Carbon Nanotube\u2013Fullerene Solar Cells", "ispublished": "pub", "full_text_status": "public", "keywords": "carbon nanomaterials; photovoltaic; bulk heterojunction; nanowires", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: June 23, 2014; Published: August 7, 2014. \n\nWork at the University of Kansas (S.R.) was supported by the Army Research Office Young Investigator Program (W911NF-14-1-0443, material design/self-assembly and photovoltaics), and Department of Energy Basic Energy Sciences Award No. DE-FG02-13ER46937 (organic synthesis and coating). Work at Northwestern University (M.C.H. and T.J.M) was supported as part of the Argonne\u2013Northwestern Solar Energy Research (ANSER) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award No. DE-SC0001059. T.A.S. and K.A.L. acknowledge graduate research fellowships through the National Science Foundation. Work at the Massachusetts Institute of Technology (M.B. and J.C.G.) was supported by an MITEI Seed Fund project. The authors thank P. Ciszek and S. Christensen at NREL for their assistance with cell certification. UPS was performed in the NUANCE facility at Northwestern University, which is supported by the NSF-MRSEC (DMR-1121262), Keck Foundation, and State of Illinois. \n\nThese authors (M.G. and T.A.S.) contributed equally to this work. M.G. designed, fabricated, and characterized inverted geometry cells. T.A.S. prepared and characterized carbon nanotube samples and interfacial layers. Y.X. and D.J. fabricated and characterized regular geometry cells. M.B. carried out DFT calculations. K.A.L. performed work function measurements. All authors discussed results and participated in the preparation of the manuscript. J.G., S.R., T.J.M., and M.C.H. supervised the project. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl5027452_si_001.pdf
", "abstract": "Single-walled carbon nanotubes (SWCNTs) have highly desirable attributes for solution-processable thin-film photovoltaics (TFPVs), such as broadband absorption, high carrier mobility, and environmental stability. However, previous TFPVs incorporating photoactive SWCNTs have utilized architectures that have limited current, voltage, and ultimately power conversion efficiency (PCE). Here, we report a solar cell geometry that maximizes photocurrent using polychiral SWCNTs while retaining high photovoltage, leading to record-high efficiency SWCNT\u2013fullerene solar cells with average NREL certified and champion PCEs of 2.5% and 3.1%, respectively. Moreover, these cells show significant absorption in the near-infrared portion of the solar spectrum that is currently inaccessible by many leading TFPV technologies.", "date": "2014-09-10", "date_type": "published", "publication": "Nano Letters", "volume": "14", "number": "9", "publisher": "American Chemical Society", "pagerange": "5308-5314", "id_number": "CaltechAUTHORS:20150923-142328234", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-142328234", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Army Research Office (ARO)", "grant_number": "W911NF-14-1-0443" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-FG02-13ER46937" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0001059" }, { "agency": "NSF Graduate Research Fellowship" }, { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "NSF", "grant_number": "DMR-1121262" }, { "agency": "W. M. Keck Foundation" }, { "agency": "State of Illinois" } ] }, "doi": "10.1021/nl5027452", "primary_object": { "basename": "nl5027452_si_001.pdf", "url": "https://authors.library.caltech.edu/records/f0rkv-6cj63/files/nl5027452_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Gong, Maogang; Shastry, Tejas A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/y24m0-awg78", "eprint_id": 60440, "eprint_status": "archive", "datestamp": "2023-08-20 02:01:24", "lastmod": "2023-10-24 16:33:44", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Risplendi-Francesca", "name": { "family": "Risplendi", "given": "Francesca" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Cicero-Giancarlo", "name": { "family": "Cicero", "given": "Giancarlo" } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Structure-property relations in amorphous carbon for photovoltaics", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 AIP Publishing LLC.\n\nReceived 5 May 2014; accepted 16 July 2014; published online 28 July 2014.\n\nThe authors thank NERSC and XSEDE for providing computational resources. This work was partially supported by the Eni Solar Frontiers Program at MIT. F.R. and G.C. acknowledge the Politecnico di Torino-MIT MITOR project funded by the Fondazione Compagnia di San Paolo.\n\nPublished - 1.4891498.pdf
", "abstract": "Carbon is emerging as a material with great potential for photovoltaics (PV). However, the amorphous form (a-C) has not been studied in detail as a PV material, even though it holds similarities with amorphous Silicon (a-Si) that is widely employed in efficient solar cells. In this work, we correlate the structure, bonding, stoichiometry, and hydrogen content of a-C with properties linked to PV performance such as the electronic structure and optical absorption. We employ first-principles molecular dynamics and density functional theory calculations to generate and analyze a set of a-C structures with a range of densities and hydrogen concentrations. We demonstrate that optical and electronic properties of interest in PV can be widely tuned by varying the density and hydrogen content. For example, sunlight absorption in a-C films can significantly exceed that of a same thickness of a-Si for a range of densities and H contents in a-C. Our results highlight promising features of a-C as the active layer material of thin-film solar cells.", "date": "2014-07-28", "date_type": "published", "publication": "Applied Physics Letters", "volume": "105", "number": "4", "publisher": "American Institute of Physics", "pagerange": "Art. No. 043903", "id_number": "CaltechAUTHORS:20150923-123623738", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-123623738", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "Fondazione Compagnia di San Paolo" } ] }, "doi": "10.1063/1.4891498", "primary_object": { "basename": "1.4891498.pdf", "url": "https://authors.library.caltech.edu/records/y24m0-awg78/files/1.4891498.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Risplendi, Francesca; Bernardi, Marco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/3vgzy-by519", "eprint_id": 60476, "eprint_status": "archive", "datestamp": "2023-08-20 01:32:37", "lastmod": "2023-10-24 16:35:18", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Vigil-Fowler-Derek", "name": { "family": "Vigil-Fowler", "given": "Derek" } }, { "id": "Lischner-Johannes", "name": { "family": "Lischner", "given": "Johannes" } }, { "id": "Neaton-Jeffrey-B", "name": { "family": "Neaton", "given": "Jeffrey B." }, "orcid": "0000-0001-7585-6135" }, { "id": "Louie-Steven-G", "name": { "family": "Louie", "given": "Steven G." } } ] }, "title": "Ab Initio Study of Hot Carriers in the First Picosecond after Sunlight Absorption in Silicon", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Physical Society.\n\nReceived 21 January 2014; published 26 June 2014.\n\nM. B. thanks Sinisa Coh for discussion. This research was supported by the SciDAC Program on Excited State Phenomena in Energy Materials funded by the U.S. Department of Energy, Office of Basic Energy Sciences and of Advanced Scientific Computing Research, under Contract No. DE-AC02-05CH11231 at Lawrence Berkeley National Laboratory, which provided for algorithm and code developments and simulations; and by the National Science Foundation under Grant No. DMR 10-1006184 which provided for basic theory and formalism. Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. S. G. L. acknowledges support of a Simons Foundation Fellowship in Theoretical Physics. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy.\n\nPublished - PhysRevLett.112.257402.pdf
", "abstract": "Hot carrier thermalization is a major source of efficiency loss in solar cells. Because of the subpicosecond time scale and complex physics involved, a microscopic characterization of hot carriers is challenging even for the simplest materials. We develop and apply an ab initio approach based on density functional theory and many-body perturbation theory to investigate hot carriers in semiconductors. Our calculations include electron-electron and electron-phonon interactions, and require no experimental input other than the structure of the material. We apply our approach to study the relaxation time and mean free path of hot carriers in Si, and map the band and k dependence of these quantities. We demonstrate that a hot carrier distribution characteristic of Si under solar illumination thermalizes within 350 fs, in excellent agreement with pump-probe experiments. Our work sheds light on the subpicosecond time scale after sunlight absorption in Si, and constitutes a first step towards ab initio quantification of hot carrier dynamics in materials.", "date": "2014-06-27", "date_type": "published", "publication": "Physical Review Letters", "volume": "112", "number": "25", "publisher": "American Physical Society", "pagerange": "Art. No. 257402", "id_number": "CaltechAUTHORS:20150924-101329607", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150924-101329607", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Department of Energy (DOE)", "grant_number": "DE-AC02-05CH11231" }, { "agency": "NSF", "grant_number": "DMR 10-1006184" }, { "agency": "Simons Foundation" } ] }, "doi": "10.1103/PhysRevLett.112.257402", "primary_object": { "basename": "PhysRevLett.112.257402.pdf", "url": "https://authors.library.caltech.edu/records/3vgzy-by519/files/PhysRevLett.112.257402.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "Bernardi, Marco; Vigil-Fowler, Derek; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/0ne2d-q5b59", "eprint_id": 60527, "eprint_status": "archive", "datestamp": "2023-08-20 00:56:30", "lastmod": "2023-10-24 16:37:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "El-Ballouli-A-O", "name": { "family": "El-Ballouli", "given": "Ala'a O." } }, { "id": "Alarousu-E", "name": { "family": "Alarousu", "given": "Erkki" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Aly-S-M", "name": { "family": "Aly", "given": "Shawkat M." } }, { "id": "Lagrow-A-P", "name": { "family": "Lagrow", "given": "Alec P." } }, { "id": "Bakr-O-M", "name": { "family": "Bakr", "given": "Osman M." } }, { "id": "Mohammed-O-F", "name": { "family": "Mohammed", "given": "Omar F." } } ] }, "title": "Quantum Confinement-Tunable Ultrafast Charge Transfer at the PbS Quantum Dot and Phenyl-C_(61)-butyric Acid Methyl Ester Interface", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2014 American Chemical Society. \n\nReceived: December 31, 2013; Published: February 12, 2014. \n\nShawkat M. Aly is grateful for the post-doctoral fellowship provided by Saudi Basic Industries Corporation (SABIC). Cover design/illustration by Anastasia Khrenova. \n\nA.O.E.-B. and E.A. contributed equally to the work. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - ja413254g_si_001.pdf
", "abstract": "Quantum dot (QD) solar cells have emerged as promising low-cost alternatives to existing photovoltaic technologies. Here, we investigate charge transfer and separation at PbS QDs and phenyl-C_(61)-butyric acid methyl ester (PCBM) interfaces using a combination of femtosecond broadband transient absorption (TA) spectroscopy and steady-state photoluminescence quenching measurements. We analyzed ultrafast electron injection and charge separation at PbS QD/PCBM interfaces for four different QD sizes and as a function of PCBM concentration. The results reveal that the energy band alignment, tuned by the quantum size effect, is the key element for efficient electron injection and charge separation processes. More specifically, the steady-state and time-resolved data demonstrate that only small-sized PbS QDs with a bandgap larger than 1 eV can transfer electrons to PCBM upon light absorption. We show that these trends result from the formation of a type-II interface band alignment, as a consequence of the size distribution of the QDs. Transient absorption data indicate that electron injection from photoexcited PbS QDs to PCBM occurs within our temporal resolution of 120 fs for QDs with bandgaps that achieve type-II alignment, while virtually all signals observed in smaller bandgap QD samples result from large bandgap outliers in the size distribution. Taken together, our results clearly demonstrate that charge transfer rates at QD interfaces can be tuned by several orders of magnitude by engineering the QD size distribution. The work presented here will advance both the design and the understanding of QD interfaces for solar energy conversion.", "date": "2014-05-14", "date_type": "published", "publication": "Journal of the American Chemical Society", "volume": "136", "number": "19", "publisher": "American Chemical Society", "pagerange": "6952-6959", "id_number": "CaltechAUTHORS:20150925-121202015", "issn": "0002-7863", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-121202015", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Saudi Basic Industries Corporation (SABIC)" } ] }, "doi": "10.1021/ja413254g", "primary_object": { "basename": "ja413254g_si_001.pdf", "url": "https://authors.library.caltech.edu/records/0ne2d-q5b59/files/ja413254g_si_001.pdf" }, "resource_type": "article", "pub_year": "2014", "author_list": "El-Ballouli, Ala'a O.; Alarousu, Erkki; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pqgj7-bf228", "eprint_id": 60452, "eprint_status": "archive", "datestamp": "2023-08-19 22:40:28", "lastmod": "2023-10-24 16:34:33", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Optimal Sunlight Harvesting in Photovoltaics and Photosynthesis", "ispublished": "pub", "full_text_status": "restricted", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: September 10, 2013; Revised: November 13, 2013; Published: November 14, 2013. \n\nThe authors acknowledge financial support from the Solar Frontiers Program at MIT. We are grateful to XSEDE for providing computational resources. \n\nThe authors declare no competing financial interest.", "abstract": "Materials employed to harvest sunlight are commonly recognized to be at a premium when their optical absorption peaks in the visible, extends to the infrared, is panchromatic, and is matched to the solar spectrum. By contrast, natural photosynthetic absorbers such as chlorophylls and carotenoids display absorption spectra with narrow peaks for yet-unknown evolutionary reasons. Beyond such general observations, a rigorous treatment of sunlight harvesting optimization is still lacking. In this work, we provide a quantitative analysis of optimal solar energy harvesting in materials. We derive optimal absorption spectra as a function of absorber thickness, elucidate the concept of solar-matched absorption and its applicability limits, and define a procedure to rank photovoltaic materials for sunlight harvesting. In addition, we suggest a possible explanation for why absorption in plant photosynthetic pigments occurs in narrow energy windows.", "date": "2013-12-27", "date_type": "published", "publication": "Journal of Physical Chemistry C", "volume": "117", "number": "51", "publisher": "American Chemical Society", "pagerange": "26896-26904", "id_number": "CaltechAUTHORS:20150923-150934426", "issn": "1932-7447", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-150934426", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "XSEDE" } ] }, "doi": "10.1021/jp4090348", "resource_type": "article", "pub_year": "2013", "author_list": "Bernardi, Marco and Grossman, Jeffrey C." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/asmtd-w6567", "eprint_id": 60451, "eprint_status": "archive", "datestamp": "2023-08-22 10:06:07", "lastmod": "2023-10-24 16:34:28", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Extraordinary Sunlight Absorption and One Nanometer Thick Photovoltaics Using Two-Dimensional Monolayer Materials", "ispublished": "pub", "full_text_status": "public", "keywords": "Monolayer materials; graphene; transition metal dichalcogenides; solar energy; sunlight absorption; photovoltaics", "note": "\u00a9 2013 American Chemical Society. \n\nReceived: April 27, 2013; Revised: June 5, 2013; Published: June 10, 2013. \n\nM.B. acknowledges fruitful discussions with Dr. David Strubbe and Dr. Can Ataca. M.P. thanks Dr. Ludger Wirtz for sharing his insight on the role of semicore electrons in GW calculations of TMD monolayers. The authors thank NERSC and XSEDE for providing computational resources. M.P. thanks CINECA for providing computational resources through the ISCRA-C project no. HP10CMAA6K. M.P. acknowledges financial support from FP7 ITN \"Clermont4\" (235114). The authors acknowledge financial support from a MITEI Seed Fund and the MISTI program. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nl401544y_si_001.pdf
", "abstract": "Graphene and monolayer transition metal dichalcogenides (TMDs) are promising materials for next-generation ultrathin optoelectronic devices. Although visually transparent, graphene is an excellent sunlight absorber, achieving 2.3% visible light absorbance in just 3.3 \u00c5 thickness. TMD monolayers also hold potential as sunlight absorbers, and may enable ultrathin photovoltaic (PV) devices due to their semiconducting character. In this work, we show that the three TMD monolayers MoS_2, MoSe_2, and WS_2 can absorb up to 5\u201310% incident sunlight in a thickness of less than 1 nm, thus achieving 1 order of magnitude higher sunlight absorption than GaAs and Si. We further study PV devices based on just two stacked monolayers: (1) a Schottky barrier solar cell between MoS_2 and graphene and (2) an excitonic solar cell based on a MoS_2/WS_2 bilayer. We demonstrate that such 1 nm thick active layers can attain power conversion efficiencies of up to \u223c1%, corresponding to approximately 1\u20133 orders of magnitude higher power densities than the best existing ultrathin solar cells. Our work shows that two-dimensional monolayer materials hold yet untapped potential for solar energy absorption and conversion at the nanoscale.", "date": "2013-08-14", "date_type": "published", "publication": "Nano Letters", "volume": "13", "number": "8", "publisher": "American Chemical Society", "pagerange": "3664-3670", "id_number": "CaltechAUTHORS:20150923-144601321", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-144601321", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Italian SuperComputing Resource Allocation (ISCRA)", "grant_number": "HP10CMAA6K" }, { "agency": "European Community Seventh Framework Programme (FP7)", "grant_number": "235114" }, { "agency": "Massachusetts Institute of Technology (MIT)" } ] }, "doi": "10.1021/nl401544y", "primary_object": { "basename": "nl401544y_si_001.pdf", "url": "https://authors.library.caltech.edu/records/asmtd-w6567/files/nl401544y_si_001.pdf" }, "resource_type": "article", "pub_year": "2013", "author_list": "Bernardi, Marco; Palummo, Maurizia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8n9xp-1xk74", "eprint_id": 60444, "eprint_status": "archive", "datestamp": "2023-08-22 08:44:39", "lastmod": "2023-10-24 16:33:59", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Kumar-Priyank-V", "name": { "family": "Kumar", "given": "Priyank V." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "The Impact of Functionalization on the Stability, Work Function, and Photoluminescence of Reduced Graphene Oxide", "ispublished": "pub", "full_text_status": "public", "keywords": "reduced graphene oxide; molecular dynamics; density functional theory; work function; stability; photoluminescence; functional groups", "note": "\u00a9 2013 American Chemical Society. \n\nReceived for review November 27, 2012 and accepted January 23, 2013. Publication Date (Web): January 31, 2013. \n\nThe authors acknowledge financial support from the Solar Frontiers Program at MIT. We thank NERSC and Teragrid for providing computational resources. \n\nThe authors declare no competing financial interest.\n\nSupplemental Material - nn305507p_si_001.pdf
Supplemental Material - nn305507p_si_002.zip
", "abstract": "Reduced graphene oxide (rGO) is a promising material for a variety of thin-film optoelectronic applications. Two main barriers to its widespread use are the lack of (1) fabrication protocols leading to tailored functionalization of the graphene sheet with oxygen-containing chemical groups, and (2) understanding of the impact of such functional groups on the stability and on the optical and electronic properties of rGO. We carry out classical molecular dynamics and density functional theory calculations on a large set of realistic rGO structures to decompose the effects of different functional groups on the stability, work function, and photoluminescence. Our calculations indicate the metastable nature of carbonyl-rich rGO and its favorable transformation to hydroxyl-rich rGO at room temperature via carbonyl-to-hydroxyl conversion reactions near carbon vacancies and holes. We demonstrate a significant tunability in the work function of rGO up to 2.5 eV by altering the composition of oxygen-containing functional groups for a fixed oxygen concentration, and of the photoluminescence emission by modulating the fraction of epoxy and carbonyl groups. Taken together, our results guide the application of tailored rGO structures in devices for optoelectronics and renewable energy.", "date": "2013-02-26", "date_type": "published", "publication": "ACS Nano", "volume": "7", "number": "2", "publisher": "American Chemical Society", "pagerange": "1638-1645", "id_number": "CaltechAUTHORS:20150923-134905213", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-134905213", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "TeraGrid" } ] }, "doi": "10.1021/nn305507p", "primary_object": { "basename": "nn305507p_si_001.pdf", "url": "https://authors.library.caltech.edu/records/8n9xp-1xk74/files/nn305507p_si_001.pdf" }, "related_objects": [ { "basename": "nn305507p_si_002.zip", "url": "https://authors.library.caltech.edu/records/8n9xp-1xk74/files/nn305507p_si_002.zip" } ], "resource_type": "article", "pub_year": "2013", "author_list": "Kumar, Priyank V.; Bernardi, Marco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/pfyr9-amq38", "eprint_id": 60447, "eprint_status": "archive", "datestamp": "2023-08-22 07:47:58", "lastmod": "2023-10-24 16:34:08", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Semiconducting Monolayer Materials as a Tunable Platform for Excitonic Solar Cells", "ispublished": "pub", "full_text_status": "public", "keywords": "photovoltaics; graphene; boron nitride; monolayer materials; band offsets; power conversion efficiency", "note": "\u00a9 2012 American Chemical Society. \n\nReceived for review August 21, 2012 and accepted October 12, 2012. Publication Date (Web): October 13, 2012. \n\nM.B. acknowledges funding from Intel through the Intel Ph.D. Fellowship. We thank NERSC and Teragrid for providing computational resources. \n\nThe authors declare no competing financial interest.\n\nSubmitted - 1206.5555.pdf
Supplemental Material - nn303815z_si_001.pdf
", "abstract": "The recent advent of two-dimensional monolayer materials with tunable optical properties and high carrier mobility offers renewed opportunities for efficient, ultrathin excitonic solar cells alternative to those based on conjugated polymer and small molecule donors. Using first-principles density functional theory and many-body calculations, we demonstrate that monolayers of hexagonal BN and graphene (CBN) combined with commonly used acceptors such as PCBM fullerene or semiconducting carbon nanotubes can provide excitonic solar cells with tunable absorber gap, donor\u2013acceptor interface band alignment, and power conversion efficiency, as well as novel device architectures. For the case of CBN\u2013PCBM devices, we predict power conversion efficiency limits in the 10\u201320% range depending on the CBN monolayer structure. Our results demonstrate the possibility of using monolayer materials in tunable, efficient, ultrathin solar cells in which unexplored exciton and carrier transport regimes are at play.", "date": "2012-11-27", "date_type": "published", "publication": "ACS Nano", "volume": "6", "number": "11", "publisher": "American Chemical Society", "pagerange": "10082-10089", "id_number": "CaltechAUTHORS:20150923-141105493", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-141105493", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Intel" }, { "agency": "TeraGrid" } ] }, "doi": "10.1021/nn303815z", "primary_object": { "basename": "1206.5555.pdf", "url": "https://authors.library.caltech.edu/records/pfyr9-amq38/files/1206.5555.pdf" }, "related_objects": [ { "basename": "nn303815z_si_001.pdf", "url": "https://authors.library.caltech.edu/records/pfyr9-amq38/files/nn303815z_si_001.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Bernardi, Marco; Palummo, Maurizia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/qs6zy-wkr32", "eprint_id": 60448, "eprint_status": "archive", "datestamp": "2023-08-22 07:12:34", "lastmod": "2023-10-24 16:34:13", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Lohrman-Jessica", "name": { "family": "Lohrman", "given": "Jessica" } }, { "id": "Kumar-Priyank-V", "name": { "family": "Kumar", "given": "Priyank V." } }, { "id": "Kirkeminde-Alec", "name": { "family": "Kirkeminde", "given": "Alec" } }, { "id": "Ferralis-Nicola", "name": { "family": "Ferralis", "given": "Nicola" } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" }, { "id": "Ren-Shenqiang", "name": { "family": "Ren", "given": "Shenqiang" } } ] }, "title": "Nanocarbon-Based Photovoltaics", "ispublished": "pub", "full_text_status": "public", "keywords": "photovoltaics; carbon; photodegradation; ab initio materials design", "note": "\u00a9 2012 American Chemical Society. \n\nReceived for review June 28, 2012 and accepted September 6, 2012. Publication Date (Web): September 6, 2012. \n\nM.B. acknowledges funding from Intel through the Intel Ph.D. Fellowship. N.F. and J.C.G. are grateful to the MITEI seed program for financial support. M.B., P.V.K., and J.C.G., wish to thank NERSC and Teragrid for providing computational resources. S.R. thanks the University of Kansas for its startup financial support, and acknowledges funding from a Department of Energy award (DESC0005448). \n\nThe authors declare no competing financial interests.\n\nSubmitted - 1206.5042.pdf
Supplemental Material - nn302893p_si_001.pdf
", "abstract": "Carbon materials are excellent candidates for photovoltaic solar cells: they are Earth-abundant, possess high optical absorption, and maintain superior thermal and photostability. Here we report on solar cells with active layers made solely of carbon nanomaterials that present the same advantages of conjugated polymer-based solar cells, namely, solution processable, potentially flexible, and chemically tunable, but with increased photostability and the possibility to revert photodegradation. The device active layer composition is optimized using ab initio density functional theory calculations to predict type-II band alignment and Schottky barrier formation. The best device fabricated is composed of PC_(70)BM fullerene, semiconducting single-walled carbon nanotubes, and reduced graphene oxide. This active-layer composition achieves a power conversion efficiency of 1.3%\u2014a record for solar cells based on carbon as the active material\u2014and we calculate efficiency limits of up to 13% for the devices fabricated in this work, comparable to those predicted for polymer solar cells employing PCBM as the acceptor. There is great promise for improving carbon-based solar cells considering the novelty of this type of device, the high photostability, and the availability of a large number of carbon materials with yet untapped potential for photovoltaics. Our results indicate a new strategy for efficient carbon-based, solution-processable, thin film, photostable solar cells.", "date": "2012-10-23", "date_type": "published", "publication": "ACS Nano", "volume": "6", "number": "10", "publisher": "American Chemical Society", "pagerange": "8896-8903", "id_number": "CaltechAUTHORS:20150923-141655695", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-141655695", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Intel" }, { "agency": "Massachusetts Institute of Technology (MIT)" }, { "agency": "TeraGrid" }, { "agency": "University of Kansas" }, { "agency": "Department of Energy (DOE)", "grant_number": "DE-SC0005448" } ] }, "doi": "10.1021/nn302893p", "primary_object": { "basename": "nn302893p_si_001.pdf", "url": "https://authors.library.caltech.edu/records/qs6zy-wkr32/files/nn302893p_si_001.pdf" }, "related_objects": [ { "basename": "1206.5042.pdf", "url": "https://authors.library.caltech.edu/records/qs6zy-wkr32/files/1206.5042.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Bernardi, Marco; Lohrman, Jessica; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/sq834-8gj44", "eprint_id": 60524, "eprint_status": "archive", "datestamp": "2023-08-19 11:16:52", "lastmod": "2023-10-24 16:37:40", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Palummo-Maurizia", "name": { "family": "Palummo", "given": "Maurizia" }, "orcid": "0000-0002-3097-8523" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Optoelectronic Properties in Monolayers of Hybridized Graphene and Hexagonal Boron Nitride", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 American Physical Society. \n\n(Received 2 February 2012; published 1 June 2012).\n\nM.\u2009B. acknowledges funding from Intel through the Intel Ph.D. Fellowship. We wish to thank NERSC for providing computational resources.\n\nPublished - PhysRevLett.108.226805.pdf
Submitted - 1204.1542v1.pdf
Supplemental Material - Figure1s.eps
Supplemental Material - Figure2s.eps
Supplemental Material - Figure3s.eps
Supplemental Material - SupplementalMaterial.pdf
Supplemental Material - SupplementalMaterial.tex
", "abstract": "We explain the nature of the electronic energy gap and optical absorption spectrum of carbon\u2013boron-nitride (CBN) monolayers using density functional theory, GW and Bethe-Salpeter calculations. The band structure and the optical absorption are regulated by the C domain size rather than the composition (as customary for bulk semiconductor alloys). The C and BN quasiparticle states lie at separate energy for C and BN, with little mixing for energies near the band edge where states are chiefly C in character. The resulting optical absorption spectra show two distinct peaks whose energy and relative intensity vary with composition in agreement with the experiment. The monolayers present strongly bound excitons localized within the C domains, with binding energies of the order of 0.5\u20131.5 eV dependent on the C domain size. The optoelectronic properties result from the overall monolayer band structure, and cannot be understood as a superposition of the properties of bulklike C and BN domains.", "date": "2012-06-01", "date_type": "published", "publication": "Physical Review Letters", "volume": "108", "number": "22", "publisher": "American Physical Society", "pagerange": "Art. No. 226805", "id_number": "CaltechAUTHORS:20150925-115740755", "issn": "0031-9007", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-115740755", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Intel" } ] }, "doi": "10.1103/PhysRevLett.108.226805", "primary_object": { "basename": "1204.1542v1.pdf", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/1204.1542v1.pdf" }, "related_objects": [ { "basename": "Figure1s.eps", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/Figure1s.eps" }, { "basename": "Figure2s.eps", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/Figure2s.eps" }, { "basename": "Figure3s.eps", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/Figure3s.eps" }, { "basename": "PhysRevLett.108.226805.pdf", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/PhysRevLett.108.226805.pdf" }, { "basename": "SupplementalMaterial.pdf", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/SupplementalMaterial.pdf" }, { "basename": "SupplementalMaterial.tex", "url": "https://authors.library.caltech.edu/records/sq834-8gj44/files/SupplementalMaterial.tex" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Bernardi, Marco; Palummo, Maurizia; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/h6rsk-70n73", "eprint_id": 60528, "eprint_status": "archive", "datestamp": "2023-08-19 10:54:16", "lastmod": "2023-10-24 16:37:56", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Ferralis-Nicola", "name": { "family": "Ferralis", "given": "Nicola" } }, { "id": "Wan-Jin-H", "name": { "family": "Wan", "given": "Jin H." } }, { "id": "Villalon-Rachelle", "name": { "family": "Villalon", "given": "Rachelle" } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Solar energy generation in three dimensions", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2012 Royal Society of Chemistry. \n\nReceived 20th January 2012, Accepted 21st February 2012. First published on the web 8th March 2012. \n\nThe authors are grateful to Vladimir Bulovic for many useful discussions. Some of the calculations were carried out at Teragrid computing facilities.\n\nPublished - C2EE21170J.pdf
Submitted - 1112.3266.pdf
Supplemental Material - c2ee21170j.mov
Supplemental Material - c2ee21170j.pdf
", "abstract": "We formulate, solve computationally and study experimentally the problem of collecting solar energy in three dimensions. We demonstrate that absorbers and reflectors can be combined in the absence of sun tracking to build three-dimensional photovoltaic (3DPV) structures that can generate measured energy densities (energy per base area, kWh/m2) higher by a factor of 2\u201320 than stationary flat PV panels for the structures considered here, compared to an increase by a factor of 1.3\u20131.8 for a flat panel with dual-axis sun tracking. The increased energy density is countered by a larger solar cell area per generated energy for 3DPV compared to flat panels (by a factor of 1.5\u20134 in our conditions), but accompanied by a vast range of improvements. 3DPV structures can mitigate some of the variability inherent to solar PV as they provide a more even source of solar energy generation at all latitudes: they can double the number of peak power generation hours and dramatically reduce the seasonal, latitude and weather variations of solar energy generation compared to a flat panel design. Self-supporting 3D shapes can create new schemes for PV installation and the increased energy density can facilitate the use of cheaper thin film materials in area-limited applications. Our findings suggest that harnessing solar energy in three dimensions can open new avenues towards Terawatt-scale generation.", "date": "2012-05-01", "date_type": "published", "publication": "Energy and Environmental Science", "volume": "5", "number": "5", "publisher": "Royal Society of Chemistry", "pagerange": "6880-6884", "id_number": "CaltechAUTHORS:20150925-122511865", "issn": "1754-5692", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-122511865", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1039/C2EE21170J", "primary_object": { "basename": "1112.3266.pdf", "url": "https://authors.library.caltech.edu/records/h6rsk-70n73/files/1112.3266.pdf" }, "related_objects": [ { "basename": "C2EE21170J.pdf", "url": "https://authors.library.caltech.edu/records/h6rsk-70n73/files/C2EE21170J.pdf" }, { "basename": "c2ee21170j.mov", "url": "https://authors.library.caltech.edu/records/h6rsk-70n73/files/c2ee21170j.mov" }, { "basename": "c2ee21170j.pdf", "url": "https://authors.library.caltech.edu/records/h6rsk-70n73/files/c2ee21170j.pdf" } ], "resource_type": "article", "pub_year": "2012", "author_list": "Bernardi, Marco; Ferralis, Nicola; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/fnbxf-fm338", "eprint_id": 60443, "eprint_status": "archive", "datestamp": "2023-08-19 08:56:48", "lastmod": "2023-10-24 16:33:53", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Ren-Shenqiang", "name": { "family": "Ren", "given": "Shenqiang" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Lunt-Richard-R", "name": { "family": "Lunt", "given": "Richard R." } }, { "id": "Bulovic-Vladimir", "name": { "family": "Bulovic", "given": "Vladimir" } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" }, { "id": "Grade\u010dak-Silvija", "name": { "family": "Grade\u010dak", "given": "Silvija" } } ] }, "title": "Toward Efficient Carbon Nanotube/P3HT Solar Cells: Active Layer Morphology, Electrical, and Optical Properties", "ispublished": "pub", "full_text_status": "public", "keywords": "Carbon nanotube, P3HT, organic photovoltaics, open-circuit voltage, dark saturation current", "note": "\u00a9 2011 American Chemical Society.\n\nReceived: August 12, 2011; Revised: October 19, 2011; Published: October 24, 2011.\n\nThis work was supported by Eni S.p.A. under the Eni-MIT Alliance Solar Frontiers Program. The authors acknowledge access to Shared Experimental Facilities provided by the MIT Center for Materials Science Engineering supported in part by MRSEC Program of National Science Foundation under award number DMR - 0213282.\n\nSupplemental Material - nl202796u_si_001.pdf
", "abstract": "We demonstrate single-walled carbon nanotube (SWCNT)/P3HT polymer bulk heterojunction solar cells with an AM1.5 efficiency of 0.72%, significantly higher than previously reported (0.05%). A key step in achieving high efficiency is the utilization of semiconducting SWCNTs coated with an ordered P3HT layer to enhance the charge separation and transport in the device active layer. Electrical characteristics of devices with SWCNT concentrations up to 40 wt % were measured and are shown to be strongly dependent on the SWCNT loading. A maximum open circuit voltage was measured for SWCNT concentration of 3 wt % with a value of 1.04 V, higher than expected based on the interface band alignment. Modeling of the open-circuit voltage suggests that despite the large carrier mobility in SWCNTs device power conversion efficiency is governed by carrier recombination. Optical characterization shows that only SWCNT with diameter of 1.3\u20131.4 nm can contribute to the photocurrent with internal quantum efficiency up to 26%. Our results advance the fundamental understanding and improve the design of efficient polymer/SWCNTs solar cells.", "date": "2011-12-14", "date_type": "published", "publication": "Nano Letters", "volume": "11", "number": "12", "publisher": "American Chemical Society", "pagerange": "5316-5321", "id_number": "CaltechAUTHORS:20150923-133855451", "issn": "1530-6984", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-133855451", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Eni-MIT Alliance Solar Frontiers Program" }, { "agency": "NSF", "grant_number": "DMR-0213282" } ] }, "doi": "10.1021/nl202796u", "primary_object": { "basename": "nl202796u_si_001.pdf", "url": "https://authors.library.caltech.edu/records/fnbxf-fm338/files/nl202796u_si_001.pdf" }, "resource_type": "article", "pub_year": "2011", "author_list": "Ren, Shenqiang; Bernardi, Marco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/6v3v4-qhv80", "eprint_id": 60529, "eprint_status": "archive", "datestamp": "2023-08-22 02:13:53", "lastmod": "2024-01-13 16:25:28", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Giulianini-Michele", "name": { "family": "Giulianini", "given": "Michele" } }, { "id": "Motta-Nunzio", "name": { "family": "Motta", "given": "Nunzio" } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Evidence of Conjugation Enhancement in P3HT/SWNT Mixtures for Organic Photovoltaics", "ispublished": "unpub", "full_text_status": "restricted", "keywords": "photovoltaic; simulation; self-assembly", "note": "\u00a9 2011 Materials Research Society. \n\nMG and NM acknowledge Dr Elena Taran and Dr Bogdan Donose (ANFF) for help with the AFM and nano-Raman measurements.", "abstract": "Classical molecular dynamics (MD) simulations in conjunction with optical absorption and AFM/nano-Raman experiments are employed to relate the molecular-scale arrangement and conjugation of poly-3-hexylthiophene (P3HT) adsorbed onto single-walled carbon nanotubes (SWNTs) and multi-walled carbon nanotubes (MWNTs). Taken together our results demonstrate the templating role of carbon nanotubes in increasing the \u03c0-conjugation length of the P3HT at the P3HT/carbon nanotube interface. The MD simulations show that SWNTs and MWNTs, due to their inherent 1-dimensional (1D) cylindrical shape and \u03c0-conjugation, planarize the P3HT molecules adsorbed at their surface and thus quench their torsional disorder, regardless of the P3HT conformation and nanotube chirality. This effect is more significant for higher SWNT weight fractions in the sample (since it is an interface effect). We investigated this effect experimentally by acquiring nano-Raman spectra in regions of high-MWNT/low-P3HT content in addition to optical absorption spectra of P3HT-SWNT composites with different SWNT concentrations. The increase in the P3HT conjugation is confirmed by a shift of a P3HT feature in the Raman spectrum when going from P3HT-rich to SWNT-rich areas in the mixture. The significance of this work for charge transfer at the P3HT-SWNT interface in bulk-heterojunction solar cells is discussed.", "date": "2011-03-02", "date_type": "published", "publisher": "Materials Research Society", "id_number": "CaltechAUTHORS:20150925-123213884", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-123213884", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "contributors": { "items": [ { "id": "Liu-J", "name": { "family": "Liu", "given": "J." } } ] }, "doi": "10.1557/opl.2011.237", "resource_type": "book_section", "pub_year": "2011", "author_list": "Bernardi, Marco; Giulianini, Michele; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/zcrmn-6vh49", "eprint_id": 60446, "eprint_status": "archive", "datestamp": "2023-08-22 01:25:04", "lastmod": "2023-10-24 16:34:02", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Giulianini-Michele", "name": { "family": "Giulianini", "given": "Michele" } }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Self-Assembly and Its Impact on Interfacial Charge Transfer in Carbon Nanotube/P3HT Solar Cells", "ispublished": "pub", "full_text_status": "public", "keywords": "self-assembly; organic photovoltaics; excitonic solar cells; bulk heterojunction; P3HT; conjugation length; carbon nanotube; molecular dynamics; charge transfer", "note": "\u00a9 2010 American Chemical Society. \n\nReceived for review July 29, 2010 and accepted October 18, 2010. Publication Date (Web): October 28, 2010. \n\nM.G. is thankful to N. Motta and J. M. Bell for support and discussion. M.G. also acknowledges support from the Queensland Government through the NIRAP project \"Solar Powered Nanosensors\" and ARCNN for the 2009 Travel Fellowship Grant. \n\nNote Added After ASAP Publication: This article was published on October 28, 2010. Figure caption and related text for Figure 1 have been corrected; an Acknowledgment has also been added. The corrected version was reposted November 23, 2010. \n\nSupporting Information: Details of the MD simulations and computational procedures; videos of a number of simulation runs of P3HT and SWNTs; preparation and experimental setup for the optical absorption measurements; additional optical spectra; discussion and estimate of the impact of the conjugation length on the interface charge transfer.\n\nSupplemental Material - nn1018297_si_001.pdf
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Supplemental Material - nn1018297_si_006.mpg
Supplemental Material - nn1018297_si_007.mpg
", "abstract": "Charge transfer at the interface of conjugated polymer and nanoscale inorganic acceptors is pivotal in determining the efficiency of excitonic solar cells. Despite intense efforts, carbon nanotube/polymer solar cells have resulted in disappointing efficiencies (<2%) due in large part to poor charge transfer at the interface. While the interfacial energy level alignment is clearly important, the self-assembly and the interface structure also play a major role in facilitating this charge transfer. To understand and control this effect to our advantage, we study the interface of commonly used conductive polymer poly-3-hexylthiophene (P3HT) and single-walled carbon nanotubes (SWNTs) with a combination of molecular dynamics simulations, absorption spectra experiments, and an analysis of charge transfer effects. Classical molecular dynamics simulations show that the P3HT wraps around the SWNTs in a number of different conformations, including helices, bundles, and more elongated conformations that maximize planar \u03c0\u2212\u03c0 stacking, in agreement with recent experimental observations. Snapshots from the MD simulations reveal that the carbon nanotubes play an important templating role of increasing the \u03c0-conjugation in the system, an effect deriving from the \u03c0\u2212\u03c0 stacking interaction at the interface and the 1-dimensional (1D) nature of the SWNTs, and independent of the SWNT chirality. We show how this increase in the system conjugation could largely improve the charge transfer in P3HT\u2212SWNT type II heterojunctions and support our results with absorption spectra measurements of mixtures of carbon nanotubes and P3HT. These findings open possibilities for improved preparation of polymeric solar cells based on carbon nanotubes and on 1D nanomaterials in general.", "date": "2010-11-23", "date_type": "published", "publication": "ACS Nano", "volume": "4", "number": "11", "publisher": "American Chemical Society", "pagerange": "6599-6606", "id_number": "CaltechAUTHORS:20150923-135830701", "issn": "1936-0851", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-135830701", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "Queensland Government" }, { "agency": "Australian Research Council Nanotechnology Network (ARCNN)" } ] }, "doi": "10.1021/nn1018297", "primary_object": { "basename": "nn1018297_si_001.pdf", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_001.pdf" }, "related_objects": [ { "basename": "nn1018297_si_002.mpg", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_002.mpg" }, { "basename": "nn1018297_si_003.mpg", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_003.mpg" }, { "basename": "nn1018297_si_004.mpg", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_004.mpg" }, { "basename": "nn1018297_si_005.mpg", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_005.mpg" }, { "basename": "nn1018297_si_006.mpg", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_006.mpg" }, { "basename": "nn1018297_si_007.mpg", "url": "https://authors.library.caltech.edu/records/zcrmn-6vh49/files/nn1018297_si_007.mpg" } ], "resource_type": "article", "pub_year": "2010", "author_list": "Bernardi, Marco; Giulianini, Michele; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8ve4p-s0g29", "eprint_id": 60531, "eprint_status": "archive", "datestamp": "2023-08-19 02:54:49", "lastmod": "2023-10-24 16:38:12", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Raja-Shilpa-N", "name": { "family": "Raja", "given": "Shilpa N." } }, { "id": "Lim-Sung-Keun", "name": { "family": "Lim", "given": "Sung Keun" } } ] }, "title": "Nanotwinned gold nanowires obtained by chemical synthesis", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 IOP Publishing. \n\nReceived 31 March 2010, in final form 23 May 2010, Published 28 June 2010. \n\nThe authors acknowledge helpful discussions with Dr Francesco Stellacci and Dr Silvija Gradecak of the Department of Materials Science at MIT.\n\nSupplemental Material - nano352522suppdata.pdf
", "abstract": "We demonstrate a facile method for synthesizing and isolating Au nanowires with a high density of twin boundary defects normal to the growth axis. In this process, oleylamine conveniently plays the role of the solvent, the reducing agent and the ligand. The geometry of the twin boundaries in the nanowires is in sharp contrast with the pentagonal twinning commonly observed in metal nanowires, and is of particular interest for its ultrahigh tensile strength. The nanostructure geometry and twin\u2013twin average spacing were characterized using high-resolution electron microscopy, and the tensile strength of the nanowires was estimated in solution using a Ti ultrasonication probe. We present a model for explaining the role of the bulky ligand oleylamine in the formation of the twin boundaries that could be extended to include elastic terms in the ligand shell. Our work demonstrates that the use of bulky, asymmetric ligands can induce extensive formation of twin boundary defects that in turn control the mechanical properties at the nanoscale.", "date": "2010-06-28", "date_type": "published", "publication": "Nanotechnology", "volume": "21", "number": "28", "publisher": "IOP", "pagerange": "Art. No. 285607", "id_number": "CaltechAUTHORS:20150925-124403422", "issn": "0957-4484", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-124403422", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1088/0957-4484/21/28/285607", "primary_object": { "basename": "nano352522suppdata.pdf", "url": "https://authors.library.caltech.edu/records/8ve4p-s0g29/files/nano352522suppdata.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "Bernardi, Marco; Raja, Shilpa N.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/7bv9y-j0563", "eprint_id": 60439, "eprint_status": "archive", "datestamp": "2023-08-19 01:39:47", "lastmod": "2023-10-24 16:33:41", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Myers-Bryan", "name": { "family": "Myers", "given": "Bryan" } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Grossman-J-C", "name": { "family": "Grossman", "given": "Jeffrey C." }, "orcid": "0000-0003-1281-2359" } ] }, "title": "Three-dimensional photovoltaics", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2010 American Institute of Physics.\n\nReceived 15 November 2009; accepted 11 January 2010; published online 16 February 2010.\n\nThis work was supported in part by NSF through the Network for Computational Nanotechnology, Grant No. EEC-0634750. We are grateful to Professor Vladimir Bulovic for helpful discussions.\n\nPublished - 1.3308490.pdf
", "abstract": "The concept of three-dimensional (3D) photovoltaics is explored computationally using a genetic algorithm to optimize the energy production in a day for arbitrarily shaped 3D solar cells confined to a given area footprint and total volume. Our simulations demonstrate that the performance of 3D photovoltaic structures scales linearly with height, leading to volumetric energy conversion, and provides power fairly evenly throughout the day. Furthermore, we show that optimal 3D structures are not simple box-like shapes, and that design attributes such as reflectivity could be optimized using three-dimensionality.", "date": "2010-02-15", "date_type": "published", "publication": "Applied Physics Letters", "volume": "96", "number": "7", "publisher": "American Institute of Physics", "pagerange": "Art. No. 071902", "id_number": "CaltechAUTHORS:20150923-123337338", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-123337338", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "funders": { "items": [ { "agency": "NSF", "grant_number": "EEC-0634750" } ] }, "doi": "10.1063/1.3308490", "primary_object": { "basename": "1.3308490.pdf", "url": "https://authors.library.caltech.edu/records/7bv9y-j0563/files/1.3308490.pdf" }, "resource_type": "article", "pub_year": "2010", "author_list": "Myers, Bryan; Bernardi, Marco; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/4ap0z-9fc52", "eprint_id": 60525, "eprint_status": "archive", "datestamp": "2023-08-20 02:35:03", "lastmod": "2023-10-24 16:37:42", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Persichetti-L", "name": { "family": "Persichetti", "given": "L." } }, { "id": "Sgarlata-Anna", "name": { "family": "Sgarlata", "given": "A." } }, { "id": "Fanfoni-Massimo", "name": { "family": "Fanfoni", "given": "M." } }, { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "M." }, "orcid": "0000-0001-7289-9666" }, { "id": "Balzarotti-Adalberto", "name": { "family": "Balzarotti", "given": "A." } } ] }, "title": "Step-step interaction on vicinal Si(001) surfaces studied by scanning tunneling microscopy", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2009 American Physical Society. \n\nReceived 18 May 2009; revised manuscript received 15 July 2009; published 21 August 2009.\n\nPublished - PhysRevB.80.075315.pdf
", "abstract": "We report on measurements of step-step interaction on a flat Si(111)\u2212(7\u00d77) surface and on vicinal Si(001) surfaces with miscut angles ranging between 0.2\u00b0 and 8\u00b0. Starting from scanning tunneling microscopy images of these surfaces and describing steps profile and interactions by the continuum step model, we measured the self-correlation function of single steps and the distribution of terrace widths. Empirical parameters, such as step stiffness and step-step interaction strength, were evaluated from the images. The present experiment allows to assess the dependence of the step-step repulsion on miscut angle, showing how parameters drawn from tunneling images can be used to interpolate between continuum mesoscopic models and atomistic calculations of vicinal surfaces.", "date": "2009-08-15", "date_type": "published", "publication": "Physical Review B", "volume": "80", "number": "7", "publisher": "American Physical Society", "pagerange": "Art. No. 075315", "id_number": "CaltechAUTHORS:20150925-120457980", "issn": "1098-0121", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-120457980", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1103/PhysRevB.80.075315", "primary_object": { "basename": "PhysRevB.80.075315.pdf", "url": "https://authors.library.caltech.edu/records/4ap0z-9fc52/files/PhysRevB.80.075315.pdf" }, "resource_type": "article", "pub_year": "2009", "author_list": "Persichetti, L.; Sgarlata, A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/14sne-8s932", "eprint_id": 60534, "eprint_status": "archive", "datestamp": "2023-08-21 21:45:12", "lastmod": "2023-10-24 16:38:14", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "M." }, "orcid": "0000-0001-7289-9666" }, { "id": "Sgarlata-Anna", "name": { "family": "Sgarlata", "given": "A." } }, { "id": "Fanfoni-Massimo", "name": { "family": "Fanfoni", "given": "M." } }, { "id": "Persichetti-L", "name": { "family": "Persichetti", "given": "L." } }, { "id": "Motta-Nunzio", "name": { "family": "Motta", "given": "N." } }, { "id": "Balzarotti-Adalberto", "name": { "family": "Balzarotti", "given": "A." } } ] }, "title": "Self-assembly of Ge quantum dots on Silicon: An example of controlled nanomanufacturing", "ispublished": "pub", "full_text_status": "restricted", "keywords": "Quantum dots; Self-assembly; Nanopatterning; SiGe epitaxy; Vicinal surfaces; Focused ion beam; Pair distribution function", "note": "\u00a9 2008 Elsevier Ltd.\n\nAvailable online 10 January 2009.\n\nThe authors gratefully thank Dario Del Moro for kindly sharing his software and his expertise in the image analysis process. We also acknowledge the kind assistance of Ernesto Placidi for the AFM measurements and the insightful discussion that followed.", "abstract": "We have grown Ge quantum dots by Physical Vapor Deposition (PVD) on step bunched Si(111) surfaces, vicinal Si(001) surfaces and oxidized Si substrates. Control of one- and two-dimensional ordering of the islands was obtained combining top-down patterning techniques (Focused Ion Beam milling), naturally occurring instabilities and anisotropies typical of Si surfaces. Real-time study of growth kinetics and self-organization of the islands has been accomplished using Scanning Tunnelling Microscopy imaging in UHV. A software routine was used to analyze the in-plane ordering of the islands on selected images. We focused on the study of the first nucleation stages of the dots on high-miscut vicinal Si(001) surfaces, in an attempt to correlate the observed behavior with the properties of these surfaces. The relevance of this research to quantum-dots based technology is also discussed.", "date": "2009-07", "date_type": "published", "publication": "Superlattices and Microstructures", "volume": "46", "number": "1-2", "publisher": "Elsevier", "pagerange": "318-323", "id_number": "CaltechAUTHORS:20150925-140624428", "issn": "0749-6036", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-140624428", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1016/j.spmi.2008.12.010", "resource_type": "article", "pub_year": "2009", "author_list": "Bernardi, M.; Sgarlata, A.; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/1q1af-x8p39", "eprint_id": 60438, "eprint_status": "archive", "datestamp": "2023-08-19 23:16:42", "lastmod": "2023-10-24 16:33:38", "type": "article", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Sgarlata-Anna", "name": { "family": "Sgarlata", "given": "Anna" } }, { "id": "Fanfoni-Massimo", "name": { "family": "Fanfoni", "given": "Massimo" } }, { "id": "Balzarotti-Adalberto", "name": { "family": "Balzarotti", "given": "Adalberto" } }, { "id": "Motta-Nunzio", "name": { "family": "Motta", "given": "Nunzio" } } ] }, "title": "A study of the pair distribution function of self-organized Ge quantum dots", "ispublished": "pub", "full_text_status": "public", "note": "\u00a9 2008 American Institute of Physics.\n\nReceived 21 May 2008; accepted 7 July 2008; published online 25 July 2008.\n\nThe authors wish to gratefully thank Dr. Dario Del Moro for kindly sharing both his software and his expertise in the image analysis process. We also acknowledge the kind assistance of Dr. Ernesto Placidi for the AFM measurements and the insightful discussion that followed.\n\nPublished - 1.2965122.pdf
", "abstract": "We explore the use of the pair distribution function to study the self-organization process of Gequantum dots on both nanopatterned and nonpatterned oxidized Si(001) surfaces.Dots formation and ordering upon annealing of a Ge thin film are analyzed. The method we use is not limited to this case study. We show how it can be applied to determine short and long range self-ordering of nanostructures. We support our results by applying a software routine to simulate patterns of dots to finally spot the relevant physical aspects of Ge islands self-assembly.", "date": "2008-07-21", "date_type": "published", "publication": "Applied Physics Letters", "volume": "93", "number": "3", "publisher": "American Institute of Physics", "pagerange": "Art. No. 031917", "id_number": "CaltechAUTHORS:20150923-122220105", "issn": "0003-6951", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150923-122220105", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1063/1.2965122", "primary_object": { "basename": "1.2965122.pdf", "url": "https://authors.library.caltech.edu/records/1q1af-x8p39/files/1.2965122.pdf" }, "resource_type": "article", "pub_year": "2008", "author_list": "Bernardi, Marco; Sgarlata, Anna; et el." }, { "id": "https://authors.library.caltech.eduhttps://authors.library.caltech.edu/records/8qxxj-z9389", "eprint_id": 60536, "eprint_status": "archive", "datestamp": "2023-08-22 11:05:23", "lastmod": "2023-10-24 16:38:23", "type": "book_section", "metadata_visibility": "show", "creators": { "items": [ { "id": "Bernardi-Marco", "name": { "family": "Bernardi", "given": "Marco" }, "orcid": "0000-0001-7289-9666" }, { "id": "Sgarlata-Anna", "name": { "family": "Sgarlata", "given": "Anna" } }, { "id": "Motta-Nunzio", "name": { "family": "Motta", "given": "Nunzio" } }, { "id": "Fanfoni-Massimo", "name": { "family": "Fanfoni", "given": "Massimo" } }, { "id": "Del-Moro-Dario", "name": { "family": "Del Moro", "given": "Dario" } }, { "id": "Balzarotti-Adalberto", "name": { "family": "Balzarotti", "given": "Adalberto" } }, { "name": { "family": "Bernardi" } } ] }, "title": "Ordering of Ge quantum dots on silicon surfaces via bottom-up and top-down approaches", "ispublished": "unpub", "full_text_status": "public", "keywords": "Quantum dots; Self-assembly; Nanopatterning; SiGe epitaxy; Vicinal surfaces; Focused Ion Beam; Nanocrystal nonvolatile memories", "note": "\u00a9 2008 IEEE.\n\nPublished - 04639268.pdf
", "abstract": "The nanoscale ordering of inorganic semiconductor quantum dots (QDs) is crucial to obtain reliable structures for novel nanotechnological applications such as nanomemories, nanolasers and nanoelectronic devices. We have directly grown Ge QDs by physical vapour deposition (PVD) on Si(111), Si(100) and some of its vicinal surfaces and studied innovative bottom up techniques to order such nanostructures. Specifically, we harnessed naturally occurring instabilities due to reconstruction and intrinsic anisotropic diffusion in Si bare surfaces, such as step bunching and natural steps occurring in silicon vicinal surfaces, to order the QDs both in one dimension and in the plane. We have also shown the use of controlled quantities of surfactants, like Sb, dramatically improves the desired ordering. Moreover, we have assisted these self-assembling processes using top-down approaches like Focused Ion Beam (FIB) milling and STM nanoindentation to control the nucleation sites and the density of the Ge QDs. Real-time study of growth and self-assembly has been accomplished using Scanning Tunneling Microscopy imaging in UHV. An explanation of the occurring processes is given, and a software routine is used to quantify the ordering of the QDs both in pre-patterned and bare surfaces. Applications, mainly in the field of Nanocrystal Nonvolatile Memories, are discussed.", "date": "2008-02", "date_type": "published", "publisher": "IEEE", "place_of_pub": "Piscataway, NJ", "pagerange": "148-151", "id_number": "CaltechAUTHORS:20150925-142125515", "isbn": "978-1-4244-1503-8", "book_title": "2008 International Conference on Nanoscience and Nanotechnology", "official_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150925-142125515", "rights": "No commercial reproduction, distribution, display or performance rights in this work are provided.", "doi": "10.1109/ICONN.2008.4639268", "primary_object": { "basename": "04639268.pdf", "url": "https://authors.library.caltech.edu/records/8qxxj-z9389/files/04639268.pdf" }, "resource_type": "book_section", "pub_year": "2008", "author_list": "Bernardi, Marco; Sgarlata, Anna; et el." } ]