1
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Robinson DA, Foster ME, Bennett CH, Bhandarkar A, Webster ER, Celebi A, Celebi N, Fuller EJ, Stavila V, Spataru CD, Ashby DS, Marinella MJ, Krishnakumar R, Allendorf MD, Talin AA. Tunable Intervalence Charge Transfer in Ruthenium Prussian Blue Analog Enables Stable and Efficient Biocompatible Artificial Synapses. Adv Mater 2023; 35:e2207595. [PMID: 36437049 DOI: 10.1002/adma.202207595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/16/2022] [Indexed: 06/16/2023]
Abstract
Emerging concepts for neuromorphic computing, bioelectronics, and brain-computer interfacing inspire new research avenues aimed at understanding the relationship between oxidation state and conductivity in unexplored materials. This report expands the materials playground for neuromorphic devices to include a mixed valence inorganic 3D coordination framework, a ruthenium Prussian blue analog (RuPBA), for flexible and biocompatible artificial synapses that reversibly switch conductance by more than four orders of magnitude based on electrochemically tunable oxidation state. The electrochemically tunable degree of mixed valency and electronic coupling between N-coordinated Ru sites controls the carrier concentration and mobility, as supported by density functional theory computations and application of electron transfer theory to in situ spectroscopy of intervalence charge transfer. Retention of programmed states is improved by nearly two orders of magnitude compared to extensively studied organic polymers, thus reducing the frequency, complexity, and energy costs associated with error correction schemes. This report demonstrates dopamine-mediated plasticity of RuPBA synapses and biocompatibility of RuPBA with neuronal cells, evoking prospective application for brain-computer interfacing.
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Affiliation(s)
| | | | | | | | | | - Aleyna Celebi
- Sandia National Laboratories, Livermore, CA, 94550, USA
| | - Nisa Celebi
- Sandia National Laboratories, Livermore, CA, 94550, USA
| | | | | | | | - David S Ashby
- Sandia National Laboratories, Livermore, CA, 94550, USA
| | - Matthew J Marinella
- School of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ, 85281, USA
| | | | | | - A Alec Talin
- Sandia National Laboratories, Livermore, CA, 94550, USA
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2
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Boehm A, Fonseca JJ, Thürmer K, Sugar JD, Spataru CD, Robinson JT, Ohta T. Engineering of Nanoscale Heterogeneous Transition Metal Dichalcogenide-Au Interfaces. Nano Lett 2023; 23:2792-2799. [PMID: 37010816 DOI: 10.1021/acs.nanolett.3c00080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Engineering the transition metal dichalcogenide (TMD)-metal interface is critical for the development of two-dimensional semiconductor devices. By directly probing the electronic structures of WS2-Au and WSe2-Au interfaces with high spatial resolution, we delineate nanoscale heterogeneities in the composite systems that give rise to local Schottky barrier height modulations. Photoelectron spectroscopy reveals large variations (>100 meV) in TMD work function and binding energies for the occupied electronic states. Characterization of the composite systems with electron backscatter diffraction and scanning tunneling microscopy leads us to attribute these heterogeneities to differing crystallite orientations in the Au contact, suggesting an inherent role of the metal microstructure in contact formation. We then leverage our understanding to develop straightforward Au processing techniques to form TMD-Au interfaces with reduced heterogeneity. Our findings illustrate the sensitivity of TMDs' electronic properties to metal contact microstructure and the viability of tuning the interface through contact engineering.
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Affiliation(s)
- Alex Boehm
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Jose J Fonseca
- Jacobs Technology Contractor at the U.S. Naval Research Laboratory, Washington, D.C. 20375, United States
| | - Konrad Thürmer
- Sandia National Laboratories, Livermore, California 94550, United States
| | - Joshua D Sugar
- Sandia National Laboratories, Livermore, California 94550, United States
| | - Catalin D Spataru
- Sandia National Laboratories, Livermore, California 94550, United States
| | | | - Taisuke Ohta
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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3
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Stavila V, Li S, Dun C, Marple MAT, Mason HE, Snider JL, Reynolds JE, El Gabaly F, Sugar JD, Spataru CD, Zhou X, Dizdar B, Majzoub EH, Chatterjee R, Yano J, Schlomberg H, Lotsch BV, Urban JJ, Wood BC, Allendorf MD. Defying Thermodynamics: Stabilization of Alane Within Covalent Triazine Frameworks for Reversible Hydrogen Storage. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202107507] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Vitalie Stavila
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Sichi Li
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | - Chaochao Dun
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | | | - Harris E. Mason
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | | | | | - Farid El Gabaly
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Joshua D. Sugar
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | | | - Xiaowang Zhou
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Brennan Dizdar
- University of Missouri—St. Louis Department of Physics and Astronomy One University Blvd St. Louis MO 63121 USA
- University of Chicago Chicago IL 60637 USA
| | - Eric H. Majzoub
- University of Missouri—St. Louis Department of Physics and Astronomy One University Blvd St. Louis MO 63121 USA
| | - Ruchira Chatterjee
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Junko Yano
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Hendrik Schlomberg
- Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 70569 Stuttgart Germany
- University of Munich (LMU) Department of Chemistry Butenandtstraße 5–13 81377 München Germany
| | - Bettina V. Lotsch
- Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 70569 Stuttgart Germany
- University of Munich (LMU) Department of Chemistry Butenandtstraße 5–13 81377 München Germany
| | - Jeffrey J. Urban
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Brandon C. Wood
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | - Mark D. Allendorf
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
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4
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Stavila V, Li S, Dun C, Marple MAT, Mason HE, Snider JL, Reynolds JE, El Gabaly F, Sugar JD, Spataru CD, Zhou X, Dizdar B, Majzoub EH, Chatterjee R, Yano J, Schlomberg H, Lotsch BV, Urban JJ, Wood BC, Allendorf MD. Rücktitelbild: Defying Thermodynamics: Stabilization of Alane Within Covalent Triazine Frameworks for Reversible Hydrogen Storage (Angew. Chem. 49/2021). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202112490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Vitalie Stavila
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Sichi Li
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | - Chaochao Dun
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | | | - Harris E. Mason
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | | | | | - Farid El Gabaly
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Joshua D. Sugar
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | | | - Xiaowang Zhou
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Brennan Dizdar
- University of Missouri—St. Louis Department of Physics and Astronomy One University Blvd St. Louis MO 63121 USA
- University of Chicago Chicago IL 60637 USA
| | - Eric H. Majzoub
- University of Missouri—St. Louis Department of Physics and Astronomy One University Blvd St. Louis MO 63121 USA
| | - Ruchira Chatterjee
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Junko Yano
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Hendrik Schlomberg
- Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 70569 Stuttgart Germany
- University of Munich (LMU) Department of Chemistry Butenandtstraße 5–13 81377 München Germany
| | - Bettina V. Lotsch
- Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 70569 Stuttgart Germany
- University of Munich (LMU) Department of Chemistry Butenandtstraße 5–13 81377 München Germany
| | - Jeffrey J. Urban
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Brandon C. Wood
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | - Mark D. Allendorf
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
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5
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Stavila V, Li S, Dun C, Marple MAT, Mason HE, Snider JL, Reynolds JE, El Gabaly F, Sugar JD, Spataru CD, Zhou X, Dizdar B, Majzoub EH, Chatterjee R, Yano J, Schlomberg H, Lotsch BV, Urban JJ, Wood BC, Allendorf MD. Defying Thermodynamics: Stabilization of Alane Within Covalent Triazine Frameworks for Reversible Hydrogen Storage. Angew Chem Int Ed Engl 2021; 60:25815-25824. [PMID: 34459093 DOI: 10.1002/anie.202107507] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 08/02/2021] [Indexed: 11/09/2022]
Abstract
The highly unfavorable thermodynamics of direct aluminum hydrogenation can be overcome by stabilizing alane within a nanoporous bipyridine-functionalized covalent triazine framework (AlH3 @CTF-bipyridine). This material and the counterpart AlH3 @CTF-biphenyl rapidly desorb H2 between 95 and 154 °C, with desorption complete at 250 °C. Sieverts measurements, 27 Al MAS NMR and 27 Al{1 H} REDOR experiments, and computational spectroscopy reveal that AlH3 @CTF-bipyridine dehydrogenation is reversible at 60 °C under 700 bar hydrogen, >10 times lower pressure than that required to hydrogenate bulk aluminum. DFT calculations and EPR measurements support an unconventional mechanism whereby strong AlH3 binding to bipyridine results in single-electron transfer to form AlH2 (AlH3 )n clusters. The resulting size-dependent charge redistribution alters the dehydrogenation/rehydrogenation thermochemistry, suggesting a novel strategy to enable reversibility in high-capacity metal hydrides.
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Affiliation(s)
- Vitalie Stavila
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Sichi Li
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
| | - Chaochao Dun
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA, 94720, USA
| | - Maxwell A T Marple
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
| | - Harris E Mason
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
| | - Jonathan L Snider
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Joseph E Reynolds
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Farid El Gabaly
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Joshua D Sugar
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Catalin D Spataru
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Xiaowang Zhou
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
| | - Brennan Dizdar
- University of Missouri-St. Louis, Department of Physics and Astronomy, One University Blvd, St. Louis, MO, 63121, USA.,University of Chicago, Chicago, IL, 60637, USA
| | - Eric H Majzoub
- University of Missouri-St. Louis, Department of Physics and Astronomy, One University Blvd, St. Louis, MO, 63121, USA
| | - Ruchira Chatterjee
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA, 94720, USA
| | - Junko Yano
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA, 94720, USA
| | - Hendrik Schlomberg
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569, Stuttgart, Germany.,University of Munich (LMU), Department of Chemistry, Butenandtstraße 5-13, 81377, München, Germany
| | - Bettina V Lotsch
- Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, 70569, Stuttgart, Germany.,University of Munich (LMU), Department of Chemistry, Butenandtstraße 5-13, 81377, München, Germany
| | - Jeffrey J Urban
- Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA, 94720, USA
| | - Brandon C Wood
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550, USA
| | - Mark D Allendorf
- Sandia National Laboratories, 7011 East Avenue, Livermore, CA, 94550, USA
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6
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Stavila V, Li S, Dun C, Marple MAT, Mason HE, Snider JL, Reynolds JE, El Gabaly F, Sugar JD, Spataru CD, Zhou X, Dizdar B, Majzoub EH, Chatterjee R, Yano J, Schlomberg H, Lotsch BV, Urban JJ, Wood BC, Allendorf MD. Back Cover: Defying Thermodynamics: Stabilization of Alane Within Covalent Triazine Frameworks for Reversible Hydrogen Storage (Angew. Chem. Int. Ed. 49/2021). Angew Chem Int Ed Engl 2021. [DOI: 10.1002/anie.202112490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Vitalie Stavila
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Sichi Li
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | - Chaochao Dun
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | | | - Harris E. Mason
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | | | | | - Farid El Gabaly
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Joshua D. Sugar
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | | | - Xiaowang Zhou
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
| | - Brennan Dizdar
- University of Missouri—St. Louis Department of Physics and Astronomy One University Blvd St. Louis MO 63121 USA
- University of Chicago Chicago IL 60637 USA
| | - Eric H. Majzoub
- University of Missouri—St. Louis Department of Physics and Astronomy One University Blvd St. Louis MO 63121 USA
| | - Ruchira Chatterjee
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Junko Yano
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Hendrik Schlomberg
- Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 70569 Stuttgart Germany
- University of Munich (LMU) Department of Chemistry Butenandtstraße 5–13 81377 München Germany
| | - Bettina V. Lotsch
- Max-Planck-Institut für Festkörperforschung Heisenbergstraße 1 70569 Stuttgart Germany
- University of Munich (LMU) Department of Chemistry Butenandtstraße 5–13 81377 München Germany
| | - Jeffrey J. Urban
- Lawrence Berkeley National Laboratory 1 Cyclotron Rd Berkeley CA 94720 USA
| | - Brandon C. Wood
- Lawrence Livermore National Laboratory 7000 East Avenue Livermore CA 94550 USA
| | - Mark D. Allendorf
- Sandia National Laboratories 7011 East Avenue Livermore CA 94550 USA
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7
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Thomas CJ, Fonseca JJ, Spataru CD, Robinson JT, Ohta T. Electronic Structure and Stacking Arrangement of Tungsten Disulfide at the Gold Contact. ACS Nano 2021; 15:18060-18070. [PMID: 34623816 DOI: 10.1021/acsnano.1c06676] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
There is an intensive effort to control the nature of attractive interactions between ultrathin semiconductors and metals and to understand its impact on the electronic properties at the junction. Here, we present a photoelectron spectroscopy study on the interface between WS2 films and gold, with a focus on the occupied electronic states near the Brillouin zone center (i.e., the Γ point). To delineate the spectra of WS2 supported on crystalline Au from the suspended WS2, we employ a microscopy approach and a tailored sample structure, in which the WS2/Au junction forms a semi-epitaxial relationship and is adjacent to suspended WS2 regions. The photoelectron spectra, as a function of WS2 thickness, display the expected splitting of the highest occupied states at the Γ point. In multilayer WS2, we discovered variations in the electronic states that spatially align with the crystalline grains of underlying Au. Corroborated by density functional theory calculations, we attribute the electronic structure variations to stacking variations within the WS2 films. We propose that strong interactions exerted by Au grains cause slippage of the interfacing WS2 layer with respect to the rest of the WS2 film. Our findings illustrate that the electronic properties of transition metal dichalcogenides, and more generally 2D layered materials, are physically altered by the interactions with the interfacing materials, in addition to the electron screening and defects that have been widely considered.
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Affiliation(s)
- Cherrelle J Thomas
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
| | - Jose J Fonseca
- National Research Council Postdoctoral Fellow at the Naval Research Laboratory, Washington, District of Columbia 20375 United States
| | - Catalin D Spataru
- Sandia National Laboratories, Livermore, California 94551, United States
| | - Jeremy T Robinson
- U.S. Naval Research Laboratory, Washington, District of Columbia 20375 United States
| | - Taisuke Ohta
- Sandia National Laboratories, Albuquerque, New Mexico 87185, United States
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8
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Cheng NLQ, Xuan F, Spataru CD, Quek SY. Charge Transfer Screening and Energy Level Alignment at Complex Organic-Inorganic Interfaces: A Tractable Ab Initio GW Approach. J Phys Chem Lett 2021; 12:8841-8846. [PMID: 34492190 DOI: 10.1021/acs.jpclett.1c02302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Complex organic-inorganic interfaces are important for device and sensing applications. Charge transfer doping is prevalent in such applications and can affect the interfacial energy level alignments (ELA), which are determined by many-body interactions. We develop an approximate ab initio many-body GW approach that can capture many-body interactions due to interfacial charge transfer. The approach uses significantly less resources than a regular GW calculation but gives excellent agreement with benchmark GW calculations on an F4TCNQ/graphene interface. We find that many-body interactions due to charge transfer screening result in gate-tunable F4TCNQ HOMO-LUMO gaps. We further predict the ELA of a large system of experimental interest-4,4'-bis(dimethylamino)bipyridine (DMAP-OED) on monolayer MoS2, where charge transfer screening results in an ∼1 eV reduction of the molecular HOMO-LUMO gap. Comparison with a two-dimensional electron gas model reveals the importance of explicitly considering the intraband transitions in determining the charge transfer screening in organic-inorganic interface systems.
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Affiliation(s)
- Nicholas Lin Quan Cheng
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, 117546 Singapore
| | - Fengyuan Xuan
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, 117546 Singapore
| | - Catalin D Spataru
- Sandia National Laboratories, Livermore, California 94551, United States
| | - Su Ying Quek
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117551 Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, 117546 Singapore
- NUS Graduate School Integrative Sciences and Engineering Programme, National University of Singapore, 117456 Singapore
- Department of Materials Science and Engineering, National University of Singapore, 9 Engineering Drive 1, 117575 Singapore
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9
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Schneemann A, Wan LF, Lipton AS, Liu YS, Snider JL, Baker AA, Sugar JD, Spataru CD, Guo J, Autrey TS, Jørgensen M, Jensen TR, Wood BC, Allendorf MD, Stavila V. Nanoconfinement of Molecular Magnesium Borohydride Captured in a Bipyridine-Functionalized Metal-Organic Framework. ACS Nano 2020; 14:10294-10304. [PMID: 32658451 DOI: 10.1021/acsnano.0c03764] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The lower limit of metal hydride nanoconfinement is demonstrated through the coordination of a molecular hydride species to binding sites inside the pores of a metal-organic framework (MOF). Magnesium borohydride, which has a high hydrogen capacity, is incorporated into the pores of UiO-67bpy (Zr6O4(OH)4(bpydc)6 with bpydc2- = 2,2'-bipyridine-5,5'-dicarboxylate) by solvent impregnation. The MOF retained its long-range order, and transmission electron microscopy and elemental mapping confirmed the retention of the crystal morphology and revealed a homogeneous distribution of the hydride within the MOF host. Notably, the B-, N-, and Mg-edge XAS data confirm the coordination of Mg(II) to the N atoms of the chelating bipyridine groups. In situ 11B MAS NMR studies helped elucidate the reaction mechanism and revealed that complete hydrogen release from Mg(BH4)2 occurs as low as 200 °C. Sieverts and thermogravimetric measurements indicate an increase in the rate of hydrogen release, with the onset of hydrogen desorption as low as 120 °C, which is approximately 150 °C lower than that of the bulk material. Furthermore, density functional theory calculations support the improved dehydrogenation properties and confirm the drastically lower activation energy for B-H bond dissociation.
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Affiliation(s)
- Andreas Schneemann
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Liwen F Wan
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Andrew S Lipton
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Yi-Sheng Liu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Jonathan L Snider
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Alexander A Baker
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Joshua D Sugar
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Catalin D Spataru
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Jinghua Guo
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Tom S Autrey
- Pacific Northwest National Laboratory, Richland, Washington 99354, United States
| | - Mathias Jørgensen
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
- Center for Materials Crystallography at the Department of Chemistry and the Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
| | - Torben R Jensen
- Center for Materials Crystallography at the Department of Chemistry and the Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus, Denmark
| | - Brandon C Wood
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - Mark D Allendorf
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
| | - Vitalie Stavila
- Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550, United States
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10
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Medlin DL, Yang N, Spataru CD, Hale LM, Mishin Y. Unraveling the dislocation core structure at a van der Waals gap in bismuth telluride. Nat Commun 2019; 10:1820. [PMID: 31015459 PMCID: PMC6478677 DOI: 10.1038/s41467-019-09815-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 03/27/2019] [Indexed: 11/08/2022] Open
Abstract
Tetradymite-structured chalcogenides such as bismuth telluride (Bi2Te3) are of significant interest for thermoelectric energy conversion and as topological insulators. Dislocations play a critical role during synthesis and processing of such materials and can strongly affect their functional properties. The dislocations between quintuple layers present special interest since their core structure is controlled by the van der Waals interactions between the layers. In this work, using atomic-resolution electron microscopy, we resolve the basal dislocation core structure in Bi2Te3, quantifying the disregistry of the atomic planes across the core. We show that, despite the existence of a stable stacking fault in the basal plane gamma surface, the dislocation core spreading is mainly due to the weak bonding between the layers, which leads to a small energy penalty for layer sliding parallel to the van der Waals gap. Calculations within a semidiscrete variational Peierls-Nabarro model informed by first-principles calculations support our experimental findings.
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Affiliation(s)
- D L Medlin
- Sandia National Laboratories, Livermore, CA, 94551, USA
| | - N Yang
- Sandia National Laboratories, Livermore, CA, 94551, USA
| | - C D Spataru
- Sandia National Laboratories, Livermore, CA, 94551, USA
| | - L M Hale
- Materials Measurement Laboratory, National Institute of Science and Technology, Gaithersburg, MD, 20899, USA
| | - Y Mishin
- Department of Physics and Astronomy, MSN 3F3, George Mason University, Fairfax, VA, 22030, USA.
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11
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Léonard F, Foster ME, Spataru CD. Prospects for Bioinspired Single-Photon Detection Using Nanotube-Chromophore Hybrids. Sci Rep 2019; 9:3268. [PMID: 30824712 PMCID: PMC6397307 DOI: 10.1038/s41598-019-39195-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Accepted: 01/16/2019] [Indexed: 11/21/2022] Open
Abstract
The human eye is an exquisite photodetection system with the ability to detect single photons. The process of vision is initiated by single-photon absorption in the molecule retinal, triggering a cascade of complex chemical processes that eventually lead to the generation of an electrical impulse. Here, we analyze the single-photon detection prospects for an architecture inspired by the human eye: field-effect transistors employing carbon nanotubes functionalized with chromophores. We employ non-equilibrium quantum transport simulations of realistic devices to reveal device response upon absorption of a single photon. We establish the parameters that determine the strength of the response such as the magnitude and orientation of molecular dipole(s), as well as the arrangements of chromophores on carbon nanotubes. Moreover, we show that functionalization of a single nanotube with multiple chromophores allows for number resolution, whereby the number of photons in an incoming light packet can be determined. Finally, we assess the performance prospects by calculating the dark count rate, and we identify the most promising architectures and regimes of operation.
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Kunakova G, Galletti L, Charpentier S, Andzane J, Erts D, Léonard F, Spataru CD, Bauch T, Lombardi F. Bulk-free topological insulator Bi 2Se 3 nanoribbons with magnetotransport signatures of Dirac surface states. Nanoscale 2018; 10:19595-19602. [PMID: 30325390 DOI: 10.1039/c8nr05500a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Many applications of topological insulators (TIs) as well as new phenomena require devices with reduced dimensions. While much progress has been made to realize thin films of TIs with low bulk carrier densities, nanostructures have not yet been reported with similar properties, despite the fact that reduced dimensions should help diminish the contributions from bulk carriers. Here we demonstrate that Bi2Se3 nanoribbons, grown by a simple catalyst-free physical-vapour deposition, have inherently low bulk carrier densities, and can be further made bulk-free by thickness reduction, thus revealing the high mobility topological surface states. Magnetotransport and Hall conductance measurements, in single nanoribbons, show that at thicknesses below 30 nm, the bulk transport is completely suppressed which is supported by self-consistent band-bending calculations. The results highlight the importance of material growth and geometrical confinement to properly exploit the unique properties of topological surface states.
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Affiliation(s)
- Gunta Kunakova
- Quantum Device Physics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, SE-41296 Gothenburg, Sweden.
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Abstract
Bilayer van der Waals (vdW) heterostructures such as MoS2/WS2 and MoSe2/WSe2 have attracted much attention recently, particularly because of their type II band alignments and the formation of interlayer exciton as the lowest-energy excitonic state. In this work, we calculate the electronic and optical properties of such heterostructures with the first-principles GW+Bethe-Salpeter Equation (BSE) method and reveal the important role of interlayer coupling in deciding the excited-state properties, including the band alignment and excitonic properties. Our calculation shows that due to the interlayer coupling, the low energy excitons can be widely tuned by a vertical gate field. In particular, the dipole oscillator strength and radiative lifetime of the lowest energy exciton in these bilayer heterostructures is varied by over an order of magnitude within a practical external gate field. We also build a simple model that captures the essential physics behind this tunability and allows the extension of the ab initio results to a large range of electric fields. Our work clarifies the physical picture of interlayer excitons in bilayer vdW heterostructures and predicts a wide range of gate-tunable excited-state properties of 2D optoelectronic devices.
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Affiliation(s)
- Shiyuan Gao
- Department of Physics, Washington University in St. Louis , St. Louis, Missouri 63136, United States
| | - Li Yang
- Department of Physics, Washington University in St. Louis , St. Louis, Missouri 63136, United States
- Institute of Materials Science and Engineering, Washington University in St. Louis , St. Louis, Missouri 63136, United States
| | - Catalin D Spataru
- Sandia National Laboratories , Livermore, California 94551, United States
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Léonard F, Spataru CD, Goldflam M, Peters DW, Beechem TE. Dynamic Wavelength-Tunable Photodetector Using Subwavelength Graphene Field-Effect Transistors. Sci Rep 2017; 8:45873. [PMID: 28374842 PMCID: PMC5379207 DOI: 10.1038/srep45873] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/03/2017] [Indexed: 11/24/2022] Open
Abstract
Dynamic wavelength tunability has long been the holy grail of photodetector technology. Because of its atomic thickness and unique properties, graphene opens up new paradigms to realize this concept, but so far this has been elusive experimentally. Here we employ detailed quantum transport modeling of photocurrent in graphene field-effect transistors (including realistic electromagnetic fields) to show that wavelength tunability is possible by dynamically changing the gate voltage. We reveal the phenomena that govern the behavior of this type of device and show significant departure from the simple expectations based on vertical transitions. We find strong focusing of the electromagnetic fields at the contact edges over the same length scale as the band-bending. Both of these spatially-varying potentials lead to an enhancement of non-vertical optical transitions, which dominate even in the absence of phonon or impurity scattering. We also show that the vanishing density of states near the Dirac point leads to contact blocking and a gate-dependent modulation of the photocurrent. Several of the effects discussed here should be applicable to a broad range of one- and two-dimensional materials and devices.
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Affiliation(s)
- François Léonard
- Sandia National Laboratories, Livermore, CA, 94551, United States
| | | | - Michael Goldflam
- Sandia National Laboratories, Albuquerque, NM, 87185, United States
| | - David W Peters
- Sandia National Laboratories, Albuquerque, NM, 87185, United States
| | - Thomas E Beechem
- Sandia National Laboratories, Albuquerque, NM, 87185, United States
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He Y, Spataru CD, Léonard F, Jones RE, Foster ME, Allendorf MD, Alec Talin A. Two-dimensional metal–organic frameworks with high thermoelectric efficiency through metal ion selection. Phys Chem Chem Phys 2017; 19:19461-19467. [DOI: 10.1039/c7cp03310a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The thermoelectric properties strongly depend on both the interaction between the metal ions and the ligands, and d orbital splitting of the metal ions induced by the ligands.
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Affiliation(s)
- Yuping He
- Sandia National Laboratories
- Livermore
- USA
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16
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Abstract
It is well-known that excitonic effects can dominate the optical properties of two-dimensional materials. These effects, however, can be substantially modified by doping free carriers. We investigate these doping effects by solving the first-principles Bethe-Salpeter equation. Dynamical screening effects, included via the sum-rule preserving generalized plasmon-pole model, are found to be important in the doped system. Using monolayer MoS2 as an example, we find that upon moderate doping, the exciton binding energy can be tuned by a few hundred millielectronvolts, while the exciton peak position stays nearly constant due to a cancellation with the quasiparticle band gap renormalization. At higher doping densities, the exciton peak position increases linearly in energy and gradually merges into a Fermi-edge singularity. Our results are crucial for the quantitative interpretation of optical properties of two-dimensional materials and the further development of ab initio theories of studying charged excitations such as trions.
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Affiliation(s)
- Shiyuan Gao
- Department of Physics, Washington University in St. Louis , St. Louis, Missouri 63130, United States
| | - Yufeng Liang
- Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Catalin D Spataru
- Sandia National Laboratories , Livermore, California 94551, United States
| | - Li Yang
- Department of Physics, Washington University in St. Louis , St. Louis, Missouri 63130, United States
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Zheng YJ, Huang YL, Chen Y, Zhao W, Eda G, Spataru CD, Zhang W, Chang YH, Li LJ, Chi D, Quek SY, Wee ATS. Heterointerface Screening Effects between Organic Monolayers and Monolayer Transition Metal Dichalcogenides. ACS Nano 2016; 10:2476-2484. [PMID: 26792247 DOI: 10.1021/acsnano.5b07314] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The nature and extent of electronic screening at heterointerfaces and their consequences on energy level alignment are of profound importance in numerous applications, such as solar cells, electronics etc. The increasing availability of two-dimensional (2D) transition metal dichalcogenides (TMDs) brings additional opportunities for them to be used as interlayers in "van der Waals (vdW) heterostructures" and organic/inorganic flexible devices. These innovations raise the question of the extent to which the 2D TMDs participate actively in dielectric screening at the interface. Here we study perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) monolayers adsorbed on single-layer tungsten diselenide (WSe2), bare graphite, and Au(111) surfaces, revealing a strong dependence of the PTCDA HOMO-LUMO gap on the electronic screening effects from the substrate. The monolayer WSe2 interlayer provides substantial, but not complete, screening at the organic/inorganic interface. Our results lay a foundation for the exploitation of the complex interfacial properties of hybrid systems based on TMD materials.
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Affiliation(s)
- Yu Jie Zheng
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
| | - Yu Li Huang
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore
| | - Yifeng Chen
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
| | - Weijie Zhao
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
| | - Goki Eda
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
- Department of Chemistry, National University of Singapore , 3 Science Drive 3, Singapore 117543, Singapore
| | - Catalin D Spataru
- Sandia National Laboratories , Livermore, California 94551, United States
| | - Wenjing Zhang
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen University , Shenzhen 518060, China
| | - Yung-Huang Chang
- Department of Electrophysics, National Chiao Tung University , Hsinchu 300, Taiwan
| | - Lain-Jong Li
- Physical Sciences and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Dongzhi Chi
- Institute of Materials Research & Engineering (IMRE), A*STAR (Agency for Science, Technology and Research) , 2 Fusionopolis Way, Innovis, Singapore 138634, Singapore
| | - Su Ying Quek
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
- Institute of High Performance Computing, Agency for Science Technology and Research , 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Singapore
| | - Andrew Thye Shen Wee
- Department of Physics, National University of Singapore , 2 Science Drive 3, Singapore 117551, Singapore
- Centre for Advanced 2D Materials, National University of Singapore , Block S14, Level 6, 6 Science Drive 2, Singapore 117546, Singapore
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18
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Erickson KJ, Léonard F, Stavila V, Foster ME, Spataru CD, Jones RE, Foley BM, Hopkins PE, Allendorf MD, Talin AA. Thin Film Thermoelectric Metal-Organic Framework with High Seebeck Coefficient and Low Thermal Conductivity. Adv Mater 2015; 27:3453-9. [PMID: 25925161 DOI: 10.1002/adma.201501078] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 04/04/2015] [Indexed: 05/20/2023]
Affiliation(s)
| | | | | | | | | | - Reese E Jones
- Sandia National Laboratories, Livermore, CA, 94551, USA
| | - Brian M Foley
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, 22904, USA
| | - Patrick E Hopkins
- Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, 22904, USA
| | | | - A Alec Talin
- Sandia National Laboratories, Livermore, CA, 94551, USA
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Spataru CD, Léonard F. Tunable band gaps and excitons in doped semiconducting carbon nanotubes made possible by acoustic plasmons. Phys Rev Lett 2010; 104:177402. [PMID: 20482140 DOI: 10.1103/physrevlett.104.177402] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2009] [Indexed: 05/29/2023]
Abstract
Doping of semiconductors is essential in modern electronic and photonic devices. While doping is well understood in bulk semiconductors, the advent of carbon nanotubes and nanowires for nanoelectronic and nanophotonic applications raises some key questions about the role and impact of doping at low dimensionality. Here we show that for semiconducting carbon nanotubes, band gaps and exciton binding energies can be dramatically reduced upon experimentally relevant doping, and can be tuned gradually over a broad range of energies in contrast with higher dimensional systems. The latter feature is made possible by a novel mechanism involving strong dynamical screening effects mediated by acoustic plasmons.
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Park CH, Giustino F, Spataru CD, Cohen ML, Louie SG. Angle-resolved photoemission spectra of graphene from first-principles calculations. Nano Lett 2009; 9:4234-4239. [PMID: 19856901 DOI: 10.1021/nl902448v] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique for directly probing electron dynamics in solids. The energy versus momentum dispersion relations and the associated spectral broadenings measured by ARPES provide a wealth of information on quantum many-body interaction effects. In particular, ARPES allows studies of the Coulomb interaction among electrons (electron-electron interactions) and the interaction between electrons and lattice vibrations (electron-phonon interactions). Here, we report ab initio simulations of the ARPES spectra of graphene including both electron-electron and electron-phonon interactions on the same footing. Our calculations reproduce some of the key experimental observations related to many-body effects, including the indication of a mismatch between the upper and lower halves of the Dirac cone.
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Affiliation(s)
- Cheol-Hwan Park
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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Park CH, Giustino F, Spataru CD, Cohen ML, Louie SG. First-principles study of electron linewidths in graphene. Phys Rev Lett 2009; 102:076803. [PMID: 19257705 DOI: 10.1103/physrevlett.102.076803] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Indexed: 05/27/2023]
Abstract
We present first-principles calculations of the linewidths of low-energy quasiparticles in n-doped graphene arising from both the electron-electron and the electron-phonon interactions. The contribution to the electron linewidth arising from the electron-electron interactions varies significantly with wave vector at fixed energy; in contrast, the electron-phonon contribution is virtually wave vector independent. These two contributions are comparable in magnitude at a binding energy of approximately 0.2 eV, corresponding to the optical phonon energy. The calculated linewidths, with both electron-electron and electron-phonon interactions included, explain to a large extent the linewidths seen in recent photoemission experiments.
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Affiliation(s)
- Cheol-Hwan Park
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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23
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Abstract
We extend previous ab initio calculations on excitonic effects in metallic single-walled carbon nanotubes to more experimentally realizable larger diameter tubes. Our calculations predict bound exciton states in both the (10,10) and (12,0) tubes with binding energies of approximately 50 meV providing experimentally verifiable changes to the absorption line shape in each case. The second and third van Hove singularities in the joint density of states also give rise to a single optically active bound or resonant excitonic state.
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Affiliation(s)
- Jack Deslippe
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA
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Park CH, Spataru CD, Louie SG. Excitons and many-electron effects in the optical response of single-walled boron nitride nanotubes. Phys Rev Lett 2006; 96:126105. [PMID: 16605933 DOI: 10.1103/physrevlett.96.126105] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Indexed: 05/08/2023]
Abstract
We report first-principles calculations of the effects of quasiparticle self-energy and electron-hole interaction on the optical properties of single-walled boron nitride nanotubes. Excitonic effects are shown to be even more important in BN nanotubes than in carbon nanotubes. Electron-hole interactions give rise to complexes of bright (and dark) excitons, which qualitatively alter the optical response. Excitons with a binding energy larger than 2 eV are found in the BN nanotubes. Moreover, unlike the carbon nanotubes, theory predicts that these exciton states are comprised of coherent supposition of transitions from several different subband pairs, giving rise to novel behaviors.
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Affiliation(s)
- Cheol-Hwan Park
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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25
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Spataru CD, Ismail-Beigi S, Capaz RB, Louie SG. Theory and ab initio calculation of radiative lifetime of excitons in semiconducting carbon nanotubes. Phys Rev Lett 2005; 95:247402. [PMID: 16384422 DOI: 10.1103/physrevlett.95.247402] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2005] [Indexed: 05/05/2023]
Abstract
We present a theoretical analysis and first-principles calculation of the radiative lifetime of excitons in semiconducting carbon nanotubes. An intrinsic lifetime of the order of 10 ps is computed for the lowest optically active bright excitons. The intrinsic lifetime is, however, a rapid increasing function of the exciton momentum. Moreover, the electronic structure of the nanotubes dictates the existence of dark excitons near in energy to each bright exciton. Both effects strongly influence measured lifetime. Assuming a thermal occupation of bright and dark exciton bands, we find an effective lifetime of the order of 10 ns at room temperature, in good accord with recent experiments.
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Affiliation(s)
- Catalin D Spataru
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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Tangney P, Capaz RB, Spataru CD, Cohen ML, Louie SG. Structural transformations of carbon nanotubes under hydrostatic pressure. Nano Lett 2005; 5:2268-73. [PMID: 16277466 DOI: 10.1021/nl051637p] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We used simulations with a classical force field to study the transformation under hydrostatic pressure of isolated single-walled nanotubes (SWNT) from a circular to a collapsed cross section. Small-diameter SWNTs deform continuously under pressure, whereas larger-diameter SWNTs display hysteresis and undergo a first-order-like transformation. The different behavior is due to the changing proportions in the total energy of the wall-curvature energy and the van der Waals attraction between opposite walls of the tube.
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Affiliation(s)
- Paul Tangney
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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Capaz RB, Spataru CD, Tangney P, Cohen ML, Louie SG. Temperature dependence of the band gap of semiconducting carbon nanotubes. Phys Rev Lett 2005; 94:036801. [PMID: 15698300 DOI: 10.1103/physrevlett.94.036801] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Indexed: 05/12/2023]
Abstract
The temperature dependence of the band gap of semiconducting single-wall carbon nanotubes (SWNTs) is calculated by direct evaluation of electron-phonon couplings within a "frozen-phonon" scheme. An interesting diameter and chirality dependence of E(g)(T) is obtained, including nonmonotonic behavior for certain tubes and distinct "family" behavior. These results are traced to a strong and complex coupling between band-edge states and the lowest-energy optical phonon modes in SWNTs. The E(g)(T) curves are modeled by an analytic function with diameter- and chirality-dependent parameters; these provide a valuable guide for systematic estimates of E(g)(T) for any given SWNT. The magnitudes of the temperature shifts at 300 K are smaller than 12 meV and should not affect (n,m) assignments based on optical measurements.
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Affiliation(s)
- Rodrigo B Capaz
- Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil
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Spataru CD, Ismail-Beigi S, Benedict LX, Louie SG. Excitonic effects and optical spectra of single-walled carbon nanotubes. Phys Rev Lett 2004; 92:077402. [PMID: 14995885 DOI: 10.1103/physrevlett.92.077402] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Indexed: 05/24/2023]
Abstract
Many-electron effects often dramatically modify the properties of reduced dimensional systems. We report calculations, based on an ab initio many-electron Green's function approach, of electron-hole interaction effects on the optical spectra of small-diameter single-walled carbon nanotubes. Excitonic effects qualitatively alter the optical spectra of both semiconducting and metallic tubes. Excitons are bound by approximately 1 eV in the semiconducting (8,0) tube and by approximately 100 meV in the metallic (3,3) tube. These large many-electron effects explain the discrepancies between previous theories and experiments.
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Affiliation(s)
- Catalin D Spataru
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720, USA
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Spataru CD, Cazalilla MA, Rubio A, Benedict LX, Echenique PM, Louie SG. Anomalous quasiparticle lifetime in graphite: band structure effects. Phys Rev Lett 2001; 87:246405. [PMID: 11736524 DOI: 10.1103/physrevlett.87.246405] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2001] [Indexed: 05/23/2023]
Abstract
We report ab initio calculations of quasiparticle lifetimes in graphite, as determined from the imaginary part of the self-energy operator within the GW approximation. The inverse lifetime in the energy range from 0.5 to 3.5 eV above the Fermi level presents significant deviations from the quadratic behavior naively expected from Fermi liquid theory. The deviations are explained in terms of the unique features of the band structure of this material. We also discuss the experimental results from different groups and make some predictions for future experiments.
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Affiliation(s)
- C D Spataru
- Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA
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