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Yuan M, Wang X, Chen X, He J, Li K, Song B, Hu H, Gao L, Lan X, Chen C, Tang J. Phase-Transfer Exchange Lead Chalcogenide Colloidal Quantum Dots: Ink Preparation, Film Assembly, and Solar Cell Construction. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2022; 18:e2102340. [PMID: 34561947 DOI: 10.1002/smll.202102340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 07/23/2021] [Indexed: 06/13/2023]
Abstract
Solution-processed colloidal quantum dots (CQDs) are promising candidates for the third-generation photovoltaics due to their low cost and spectral tunability. The development of CQD solar cells mainly relies on high-quality CQD ink, smooth and dense film, and charge-extraction-favored device architectures. In particular, advances in the processing of CQDs are essential for high-quality QD solids. The phase transfer exchange (PTE), in contrast with traditional solid-state ligand exchange, has demonstrated to be the most promising approach for high-quality QD solids in terms of charge transport and defect passivation. As a result, the efficiencies of Pb chalcogenide CQD solar cells have been rapidly improved to 14.0%. In this review, the development of the PTE method is briefly reviewed for lead chalcogenide CQD ink preparation, film assembly, and device construction. Particularly, the key roles of lead halides and additional additives are emphasized for defect passivation and charge transport improvement. In the end, several potential directions for future research are proposed.
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Affiliation(s)
- Mohan Yuan
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, P. R. China
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Xia Wang
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, P. R. China
| | - Xiao Chen
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, P. R. China
| | - Jungang He
- Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, P. R. China
| | - Kanghua Li
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Boxiang Song
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Huicheng Hu
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Liang Gao
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Xinzheng Lan
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Chao Chen
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
| | - Jiang Tang
- Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, P. R. China
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2
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Nakotte T, Luo H, Pietryga J. PbE (E = S, Se) Colloidal Quantum Dot-Layered 2D Material Hybrid Photodetectors. NANOMATERIALS (BASEL, SWITZERLAND) 2020; 10:E172. [PMID: 31963894 PMCID: PMC7022979 DOI: 10.3390/nano10010172] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 02/04/2023]
Abstract
Hybrid lead chalcogenide (PbE) (E = S, Se) quantum dot (QD)-layered 2D systems are an emerging class of photodetectors with unique potential to expand the range of current technologies and easily integrate into current complementary metal-oxide-semiconductor (CMOS)-compatible architectures. Herein, we review recent advancements in hybrid PbE QD-layered 2D photodetectors and place them in the context of key findings from studies of charge transport in layered 2D materials and QD films that provide lessons to be applied to the hybrid system. Photodetectors utilizing a range of layered 2D materials including graphene and transition metal dichalcogenides sensitized with PbE QDs in various device architectures are presented. Figures of merit such as responsivity (R) and detectivity (D*) are reviewed for a multitude of devices in order to compare detector performance. Finally, a look to the future considers possible avenues for future device development, including potential new materials and device treatment/fabrication options.
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Affiliation(s)
- Tom Nakotte
- Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM 88003, USA;
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA;
| | - Hongmei Luo
- Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM 88003, USA;
| | - Jeff Pietryga
- Chemistry Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA;
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3
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Kuhs J, Werbrouck A, Zawacka N, Drijvers E, Smet PF, Hens Z, Detavernier C. In Situ Photoluminescence of Colloidal Quantum Dots During Gas Exposure-The Role of Water and Reactive Atomic Layer Deposition Precursors. ACS APPLIED MATERIALS & INTERFACES 2019; 11:26277-26287. [PMID: 31260622 DOI: 10.1021/acsami.9b08259] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Colloidal quantum dots (QDs) are a promising material for optoelectronic applications. Typically, device integration requires QDs to be embedded in a host material. Atomic layer deposition (ALD) is often considered as a deposition technique for such purposes. However, it is known that ALD and vacuum processes often influence the optical properties of QDs in a negative way. Here, we describe an in situ photoluminescence (PL) measurement setup and use it to monitor the PL of QDs under vacuum and during ALD. For CdSe-based core/shell QDs, a reduction in the QD PL was observed upon exposure to vacuum. Water was identified as crucial for maintaining a high PL as evidenced by re-exposure to different gases. Furthermore, we addressed the influence of vacuum, different plasmas (O2, H2O, H2, H2S/Ar, and Ar), precursors (trimethylaluminum, diethylzinc, tetrakis(dimethylamido)titanium, and tetrakis(ethylmethylamido)hafnium), reactants (H2O, H2S, and O3), and ALD processes (Al2O3, TiO2, HfO2, and ZnS) on QDs. We observed a PL reduction by up to 90% upon plasma treatments. Furthermore, we found that trimethylaluminum and diethylzinc reduced the PL efficiency by more than 70% while exposure to tetrakis(dimethylamido)titanium and tetrakis(ethylmethylamido)hafnium lowered the PL by only 10-20%. Surprisingly, tetrakis(dimethylamido)titanium and H2O, which by themselves had only a minor influence on the QD PL, still caused an 80% drop of the PL efficiency when combined as an ALD process. On the other hand, ALD growth of HfO2 by combining tetrakis(ethylmethylamido)hafnium and O3 preserved 80% of the initial PL quantum yield, making it a promising process for QD embedding. These results put forward in situ PL measurements as a versatile technique to identify suitable precursors, reactants and ALD processes for QD embedding and investigate the interaction between QDs and reactive gaseous species in general.
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Affiliation(s)
- Jakob Kuhs
- Department of Solid State Sciences, CoCooN , Ghent University , Krijgslaan 281/S1 , 9000 Ghent , Belgium
| | - Andreas Werbrouck
- Department of Solid State Sciences, CoCooN , Ghent University , Krijgslaan 281/S1 , 9000 Ghent , Belgium
| | - Natalia Zawacka
- Department of Inorganic and Physical Chemistry, PCN , Ghent University , Krijgslaan 281/S3 , 9000 Ghent , Belgium
| | - Emile Drijvers
- Department of Inorganic and Physical Chemistry, PCN , Ghent University , Krijgslaan 281/S3 , 9000 Ghent , Belgium
| | - Philippe F Smet
- Department of Solid State Sciences, LumiLab , Ghent University , Krijgslaan 281/S1 , 9000 Ghent , Belgium
| | - Zeger Hens
- Department of Inorganic and Physical Chemistry, PCN , Ghent University , Krijgslaan 281/S3 , 9000 Ghent , Belgium
| | - Christophe Detavernier
- Department of Solid State Sciences, CoCooN , Ghent University , Krijgslaan 281/S1 , 9000 Ghent , Belgium
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Abstract
From a niche field over 30 years ago, quantum dots (QDs) have developed into viable materials for many commercial optoelectronic devices. We discuss the advancements in Pb-based QD solar cells (QDSCs) from a viewpoint of the pathways an excited state can take when relaxing back to the ground state. Systematically understanding the fundamental processes occurring in QDs has led to improvements in solar cell efficiency from ~3% to over 13% in 8 years. We compile data from ~200 articles reporting functioning QDSCs to give an overview of the current limitations in the technology. We find that the open circuit voltage limits the device efficiency and propose some strategies for overcoming this limitation.
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5
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Chang IY, Kim D, Hyeon-Deuk K. Control of Multiple Exciton Generation and Electron-Phonon Coupling by Interior Nanospace in Hyperstructured Quantum Dot Superlattice. ACS APPLIED MATERIALS & INTERFACES 2017; 9:32080-32088. [PMID: 28838230 DOI: 10.1021/acsami.7b08137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The possibility of precisely manipulating interior nanospace, which can be adjusted by ligand-attaching down to the subnanometer regime, in a hyperstructured quantum dot (QD) superlattice (QDSL) induces a new kind of collective resonant coupling among QDs and opens up new opportunities for developing advanced optoelectric and photovoltaic devices. Here, we report the first real-time dynamics simulations of the multiple exciton generation (MEG) in one-, two-, and three-dimensional (1D, 2D, and 3D) hyperstructured H-passivated Si QDSLs, accounting for thermally fluctuating band energies and phonon dynamics obtained by finite-temperature ab initio molecular dynamics simulations. We computationally demonstrated that the MEG was significantly accelerated, especially in the 3D QDSL compared to the 1D and 2D QDSLs. The MEG acceleration in the 3D QDSL was almost 1.9 times the isolated QD case. The dimension-dependent MEG acceleration was attributed not only to the static density of states but also to the dynamical electron-phonon couplings depending on the dimensionality of the hyperstructured QDSL, which is effectively controlled by the interior nanospace. Such dimension-dependent modifications originated from the short-range quantum resonance among component QDs and were intrinsic to the hyperstructured QDSL. We propose that photoexcited dynamics including the MEG process can be effectively controlled by only manipulating the interior nanospace of the hyperstructured QDSL without changing component QD size, shape, compositions, ligand, etc.
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Affiliation(s)
- I-Ya Chang
- Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan
- PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - DaeGwi Kim
- Department of Applied Physics, Osaka City University , Osaka 558-8585, Japan
| | - Kim Hyeon-Deuk
- Department of Chemistry, Kyoto University , Kyoto 606-8502, Japan
- PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
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6
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Kershaw SV, Rogach AL. Carrier Multiplication Mechanisms and Competing Processes in Colloidal Semiconductor Nanostructures. MATERIALS (BASEL, SWITZERLAND) 2017; 10:E1095. [PMID: 28927007 PMCID: PMC5615749 DOI: 10.3390/ma10091095] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/10/2017] [Accepted: 09/14/2017] [Indexed: 12/14/2022]
Abstract
Quantum confined semiconductor nanoparticles, such as colloidal quantum dots, nanorods and nanoplatelets have broad extended absorption spectra at energies above their bandgaps. This means that they can absorb light at high photon energies leading to the formation of hot excitons with finite excited state lifetimes. During their existence, the hot electron and hole that comprise the exciton may start to cool as they relax to the band edge by phonon mediated or Auger cooling processes or a combination of these. Alongside these cooling processes, there is the possibility that the hot exciton may split into two or more lower energy excitons in what is termed carrier multiplication (CM). The fission of the hot exciton to form lower energy multiexcitons is in direct competition with the cooling processes, with the timescales for multiplication and cooling often overlapping strongly in many materials. Once CM has been achieved, the next challenge is to preserve the multiexcitons long enough to make use of the bonus carriers in the face of another competing process, non-radiative Auger recombination. However, it has been found that Auger recombination and the several possible cooling processes can be manipulated and usefully suppressed or retarded by engineering the nanoparticle shape, size or composition and by the use of heterostructures, along with different choices of surface treatments. This review surveys some of the work that has led to an understanding of the rich carrier dynamics in semiconductor nanoparticles, and that has started to guide materials researchers to nanostructures that can tilt the balance in favour of efficient CM with sustained multiexciton lifetimes.
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Affiliation(s)
- Stephen V Kershaw
- Department of Materials Science and Engineering and Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong S.A.R., China.
| | - Andrey L Rogach
- Department of Materials Science and Engineering and Centre for Functional Photonics (CFP), City University of Hong Kong, Hong Kong S.A.R., China.
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Ivanou D, Ivanova YA, Poznyak S, Starykevich M, Ferreira M, Mendes A, Streltsov E. Spectral sensitization of TiO 2 with electrodeposited PbSe: improvement of photocurrent stability and light conversion efficiency. Electrochim Acta 2017. [DOI: 10.1016/j.electacta.2017.08.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Qu L, Vörös M, Zimanyi GT. Metal-Insulator Transition in Nanoparticle Solids: Insights from Kinetic Monte Carlo Simulations. Sci Rep 2017; 7:7071. [PMID: 28765599 PMCID: PMC5539282 DOI: 10.1038/s41598-017-06497-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/13/2017] [Indexed: 11/09/2022] Open
Abstract
Progress has been rapid in increasing the efficiency of energy conversion in nanoparticles. However, extraction of the photo-generated charge carriers remains challenging. Encouragingly, the charge mobility has been improved recently by driving nanoparticle (NP) films across the metal-insulator transition (MIT). To simulate MIT in NP films, we developed a hierarchical Kinetic Monte Carlo transport model. Electrons transfer between neighboring NPs via activated hopping when the NP energies differ by more than an overlap energy, but transfer by a non-activated quantum delocalization, if the NP energies are closer than the overlap energy. As the overlap energy increases, emerging percolating clusters support a metallic transport across the entire film. We simulated the evolution of the temperature-dependent electron mobility. We analyzed our data in terms of two candidate models of the MIT: (a) as a Quantum Critical Transition, signaled by an effective gap going to zero; and (b) as a Quantum Percolation Transition, where a sample-spanning metallic percolation path is formed as the fraction of the hopping bonds in the transport paths is going to zero. We found that the Quantum Percolation Transition theory provides a better description of the MIT. We also observed an anomalously low gap region next to the MIT. We discuss the relevance of our results in the light of recent experimental measurements.
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Affiliation(s)
- Luman Qu
- Physics Department, University of California, Davis, USA
| | - Márton Vörös
- Materials Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
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9
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Pietryga JM, Park YS, Lim J, Fidler AF, Bae WK, Brovelli S, Klimov VI. Spectroscopic and Device Aspects of Nanocrystal Quantum Dots. Chem Rev 2017; 116:10513-622. [PMID: 27677521 DOI: 10.1021/acs.chemrev.6b00169] [Citation(s) in RCA: 390] [Impact Index Per Article: 55.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The field of nanocrystal quantum dots (QDs) is already more than 30 years old, and yet continuing interest in these structures is driven by both the fascinating physics emerging from strong quantum confinement of electronic excitations, as well as a large number of prospective applications that could benefit from the tunable properties and amenability toward solution-based processing of these materials. The focus of this review is on recent advances in nanocrystal research related to applications of QD materials in lasing, light-emitting diodes (LEDs), and solar energy conversion. A specific underlying theme is innovative concepts for tuning the properties of QDs beyond what is possible via traditional size manipulation, particularly through heterostructuring. Examples of such advanced control of nanocrystal functionalities include the following: interface engineering for suppressing Auger recombination in the context of QD LEDs and lasers; Stokes-shift engineering for applications in large-area luminescent solar concentrators; and control of intraband relaxation for enhanced carrier multiplication in advanced QD photovoltaics. We examine the considerable recent progress on these multiple fronts of nanocrystal research, which has resulted in the first commercialized QD technologies. These successes explain the continuing appeal of this field to a broad community of scientists and engineers, which in turn ensures even more exciting results to come from future exploration of this fascinating class of materials.
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Affiliation(s)
- Jeffrey M Pietryga
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Young-Shin Park
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States.,Center for High Technology Materials, University of New Mexico , Albuquerque, New Mexico 87131, United States
| | - Jaehoon Lim
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Andrew F Fidler
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
| | - Wan Ki Bae
- Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology , Seoul 02792, Korea
| | - Sergio Brovelli
- Dipartimento di Scienza dei Materiali, Università degli Studi di Milano-Bicocca , I-20125 Milano, Italy
| | - Victor I Klimov
- Nanotechnology and Advanced Spectroscopy Team, Chemistry Division, Los Alamos National Laboratory , Los Alamos, New Mexico 87545, United States
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Nemati Aram T, Anghel-Vasilescu P, Asgari A, Ernzerhof M, Mayou D. Modeling of molecular photocells: Application to two-level photovoltaic system with electron-hole interaction. J Chem Phys 2016; 145:124116. [DOI: 10.1063/1.4963335] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Affiliation(s)
- Tahereh Nemati Aram
- Institut Néel, CNRS and Université Grenoble Alpes, Grenoble F-38042, France
- Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz 51665-163, Iran
| | | | - Asghar Asgari
- Research Institute for Applied Physics and Astronomy, University of Tabriz, Tabriz 51665-163, Iran
- School of Electrical, Electronic and Computer Engineering, The University of Western Australia, Crawley, WA 6009, Australia
| | - Matthias Ernzerhof
- Département de Chimie, Université de Montréal, C.P. 6128 Succursale A, Montréal, Québec H3C 3J7, Canada
| | - Didier Mayou
- Institut Néel, CNRS and Université Grenoble Alpes, Grenoble F-38042, France
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11
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King LA, Parkinson BA. Photosensitization of ZnO Crystals with Iodide-Capped PbSe Quantum Dots. J Phys Chem Lett 2016; 7:2844-2848. [PMID: 27398873 DOI: 10.1021/acs.jpclett.6b01133] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Lead selenide (PbSe) quantum dots (QDs) are an attractive material for application in photovoltaic devices due to the ability to tune their band gap, efficient multiple exciton generation, and high extinction coefficients. However, PbSe QDs are quite unstable to oxidation in air. Recently there have been multiple studies detailing postsynthetic halide treatments to stabilize lead chalcogenide QDs. We exploit iodide-stabilized PbSe QDs in a model QD-sensitized solar cell configuration where zinc oxide (ZnO) single crystals are sensitized using cysteine as a bifunctional linker molecule. Sensitized photocurrents stable for >1 h can be measured in aqueous KI electrolyte that is usually corrosive to QDs under illumination. The spectral response of the sensitization extended out to 1700 nm, the farthest into the infrared yet observed. Hints of the existence of multiple exciton generation and collection as photocurrent, as would be expected in this system, are speculated and discussed.
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Affiliation(s)
- Laurie A King
- Department of Chemistry and School of Energy Resources, University of Wyoming , 1000 East University, Laramie, Wyoming 82071, United States
| | - B A Parkinson
- Department of Chemistry and School of Energy Resources, University of Wyoming , 1000 East University, Laramie, Wyoming 82071, United States
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12
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The effects of inorganic surface treatments on photogenerated carrier mobility and lifetime in PbSe quantum dot thin films. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2015.07.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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13
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Treml B, Yang J, Wise F, Hanrath T. Simultaneous ligand and cation exchange in PbSe/CdSe nanocrystal films. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2015.07.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Kumar M, Vezzoli S, Wang Z, Chaudhary V, Ramanujan RV, Gurzadyan GG, Bruno A, Soci C. Hot exciton cooling and multiple exciton generation in PbSe quantum dots. Phys Chem Chem Phys 2016; 18:31107-31114. [DOI: 10.1039/c6cp03790a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PbSe QDs show high multiple exciton generation (MEG) quantum yield. Here we have investigated the role of theΣtransition in slowing down the hot exciton cooling, which can help MEG to take over phonon relaxation.
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Affiliation(s)
- Manoj Kumar
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore
- Singapore
| | - Stefano Vezzoli
- Centre for Disruptive Photonic Technologies
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore
- Singapore
| | - Zilong Wang
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore
- Singapore
| | - Varun Chaudhary
- Interdisciplinary Graduate School (IGS)
- Nanyang Technological University
- Singapore
- Singapore
- School of Materials Science and Engineering
| | - Raju V. Ramanujan
- School of Materials Science and Engineering
- Nanyang Technological University
- Singapore 639798
- Singapore
| | - Gagik G. Gurzadyan
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore
- Singapore
| | - Annalisa Bruno
- Energy Research Institute @ NTU (ERI@N)
- Research Techno Plaza
- Singapore
- Singapore
| | - Cesare Soci
- Division of Physics and Applied Physics
- School of Physical and Mathematical Sciences
- Nanyang Technological University
- Singapore
- Singapore
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15
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Crisp RW, Callahan R, Reid OG, Dolzhnikov DS, Talapin DV, Rumbles G, Luther JM, Kopidakis N. Photoconductivity of CdTe Nanocrystal-Based Thin Films: Te(2-) Ligands Lead To Charge Carrier Diffusion Lengths Over 2 μm. J Phys Chem Lett 2015; 6:4815-21. [PMID: 26571095 DOI: 10.1021/acs.jpclett.5b02252] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We report on photoconductivity of films of CdTe nanocrystals (NCs) using time-resolved microwave photoconductivity (TRMC). Spherical and tetrapodal CdTe NCs with tunable size-dependent properties are studied as a function of surface ligand (including inorganic molecular chalcogenide species) and annealing temperature. Relatively high carrier mobility is measured for films of sintered tetrapod NCs (4 cm(2)/(V s)). Our TRMC findings show that Te(2-) capped CdTe NCs show a marked improvement in carrier mobility (11 cm(2)/(V s)), indicating that NC surface termination can be altered to play a crucial role in charge-carrier mobility even after the NC solids are sintered into bulk films.
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Affiliation(s)
- Ryan W Crisp
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
- Department of Physics, Colorado School of Mines , Golden, Colorado 80401, United States
| | - Rebecca Callahan
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
- Department of Chemistry and Biochemistry, University of Colorado , Boulder, Colorado 80309, United States
| | - Obadiah G Reid
- Renewable and Sustainable Energy Institute, University of Colorado at Boulder , Boulder, Colorado 80309, United States
| | - Dmitriy S Dolzhnikov
- Department of Chemistry, University of Chicago , Chicago, Illinois 60637, United States
| | - Dmitri V Talapin
- Department of Chemistry, University of Chicago , Chicago, Illinois 60637, United States
| | - Garry Rumbles
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
| | - Joseph M Luther
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
| | - Nikos Kopidakis
- National Renewable Energy Laboratory , Golden, Colorado 80401, United States
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16
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Palmstrom AF, Santra PK, Bent SF. Atomic layer deposition in nanostructured photovoltaics: tuning optical, electronic and surface properties. NANOSCALE 2015; 7:12266-12283. [PMID: 26147328 DOI: 10.1039/c5nr02080h] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nanostructured materials offer key advantages for third-generation photovoltaics, such as the ability to achieve high optical absorption together with enhanced charge carrier collection using low cost components. However, the extensive interfacial areas in nanostructured photovoltaic devices can cause high recombination rates and a high density of surface electronic states. In this feature article, we provide a brief review of some nanostructured photovoltaic technologies including dye-sensitized, quantum dot sensitized and colloidal quantum dot solar cells. We then introduce the technique of atomic layer deposition (ALD), which is a vapor phase deposition method using a sequence of self-limiting surface reaction steps to grow thin, uniform and conformal films. We discuss how ALD has established itself as a promising tool for addressing different aspects of nanostructured photovoltaics. Examples include the use of ALD to synthesize absorber materials for both quantum dot and plasmonic solar cells, to grow barrier layers for dye and quantum dot sensitized solar cells, and to infiltrate coatings into colloidal quantum dot solar cell to improve charge carrier mobilities as well as stability. We also provide an example of monolayer surface modification in which adsorbed ligand molecules on quantum dots are used to tune the band structure of colloidal quantum dot solar cells for improved charge collection. Finally, we comment on the present challenges and future outlook of the use of ALD for nanostructured photovoltaics.
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Affiliation(s)
- Axel F Palmstrom
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, USA.
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Marshall AR, Young MR, Nozik AJ, Beard MC, Luther JM. Exploration of Metal Chloride Uptake for Improved Performance Characteristics of PbSe Quantum Dot Solar Cells. J Phys Chem Lett 2015; 6:2892-2899. [PMID: 26267176 DOI: 10.1021/acs.jpclett.5b01214] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We explored the uptake of metal chloride salts with +1 to +3 metals of Na(+), K(+), Zn(2+), Cd(2+), Sn(2+), Cu(2+), and In(3+) by PbSe QD solar cells. We also compared CdCl2 to Cd acetate and Cd nitrate treatments. PbSe QD solar cells fabricated with a CdCl2 treatment are stable for more than 270 days stored in air. We studied how temperature and immersion times affect optoelectronic properties and photovoltaic cell performance. Uptake of Cd(2+) and Zn(2+) increase open circuit voltage, whereas In(3+) and K(+) increase the photocurrent without influencing the spectral response or first exciton peak position. Using the most beneficial treatments we varied the bandgap of PbSe QD solar cells from 0.78 to 1.3 eV and find the improved VOC is more prevalent for lower bandgap QD solar cells.
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Affiliation(s)
- Ashley R Marshall
- †National Renewable Energy Laboratory, Golden, Colorado 80401, United States
- ‡Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Matthew R Young
- †National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Arthur J Nozik
- †National Renewable Energy Laboratory, Golden, Colorado 80401, United States
- ‡Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Matthew C Beard
- †National Renewable Energy Laboratory, Golden, Colorado 80401, United States
| | - Joseph M Luther
- †National Renewable Energy Laboratory, Golden, Colorado 80401, United States
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ten Cate S, Sandeep CSS, Liu Y, Law M, Kinge S, Houtepen AJ, Schins JM, Siebbeles LDA. Generating free charges by carrier multiplication in quantum dots for highly efficient photovoltaics. Acc Chem Res 2015; 48:174-81. [PMID: 25607377 DOI: 10.1021/ar500248g] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONSPECTUS: In a conventional photovoltaic device (solar cell or photodiode) photons are absorbed in a bulk semiconductor layer, leading to excitation of an electron from a valence band to a conduction band. Directly after photoexcitation, the hole in the valence band and the electron in the conduction band have excess energy given by the difference between the photon energy and the semiconductor band gap. In a bulk semiconductor, the initially hot charges rapidly lose their excess energy as heat. This heat loss is the main reason that the theoretical efficiency of a conventional solar cell is limited to the Shockley-Queisser limit of ∼33%. The efficiency of a photovoltaic device can be increased if the excess energy is utilized to excite additional electrons across the band gap. A sufficiently hot charge can produce an electron-hole pair by Coulomb scattering on a valence electron. This process of carrier multiplication (CM) leads to formation of two or more electron-hole pairs for the absorption of one photon. In bulk semiconductors such as silicon, the energetic threshold for CM is too high to be of practical use. However, CM in nanometer sized semiconductor quantum dots (QDs) offers prospects for exploitation in photovoltaics. CM leads to formation of two or more electron-hole pairs that are initially in close proximity. For photovoltaic applications, these charges must escape from recombination. This Account outlines our recent progress in the generation of free mobile charges that result from CM in QDs. Studies of charge carrier photogeneration and mobility were carried out using (ultrafast) time-resolved laser techniques with optical or ac conductivity detection. We found that charges can be extracted from photoexcited PbS QDs by bringing them into contact with organic electron and hole accepting materials. However, charge localization on the QD produces a strong Coulomb attraction to its counter charge in the organic material. This limits the production of free charges that can contribute to the photocurrent in a device. We show that free mobile charges can be efficiently produced via CM in solids of strongly coupled PbSe QDs. Strong electronic coupling between the QDs resulted in a charge carrier mobility of the order of 1 cm(2) V(-1) s(-1). This mobility is sufficiently high so that virtually all electron-hole pairs escape from recombination. The impact of temperature on the CM efficiency in PbSe QD solids was also studied. We inferred that temperature has no observable effect on the rate of cooling of hot charges nor on the CM rate. We conclude that exploitation of CM requires that charges have sufficiently high mobility to escape from recombination. The contribution of CM to the efficiency of photovoltaic devices can be further enhanced by an increase of the CM efficiency above the energetic threshold of twice the band gap. For large-scale applications in photovoltaic devices, it is important to develop abundant and nontoxic materials that exhibit efficient CM.
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Affiliation(s)
- Sybren ten Cate
- Optoelectronic Materials Section, Department of Chemical
Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - C. S. Suchand Sandeep
- Optoelectronic Materials Section, Department of Chemical
Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Yao Liu
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Matt Law
- Department of Chemistry, University of California, Irvine, Irvine, California 92697, United States
| | - Sachin Kinge
- Toyota Motor Europe, Functional Nanomaterials Lab, Advanced Technology, Hoge Wei 33, B-1930 Zaventem, Belgium
| | - Arjan J. Houtepen
- Optoelectronic Materials Section, Department of Chemical
Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Juleon M. Schins
- Optoelectronic Materials Section, Department of Chemical
Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
| | - Laurens D. A. Siebbeles
- Optoelectronic Materials Section, Department of Chemical
Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands
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Kim MR, Ma D. Quantum-Dot-Based Solar Cells: Recent Advances, Strategies, and Challenges. J Phys Chem Lett 2015; 6:85-99. [PMID: 26263096 DOI: 10.1021/jz502227h] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Among next-generation photovoltaic systems requiring low cost and high efficiency, quantum dot (QD)-based solar cells stand out as a very promising candidate because of the unique and versatile characteristics of QDs. The past decade has already seen rapid conceptual and technological advances on various aspects of QD solar cells, and diverse opportunities, which QDs can offer, predict that there is still ample room for further development and breakthroughs. In this Perspective, we first review the attractive advantages of QDs, such as size-tunable band gaps and multiple exciton generation (MEG), beneficial to solar cell applications. We then analyze major strategies, which have been extensively explored and have largely contributed to the most recent and significant achievements in QD solar cells. Finally, their high potential and challenges are discussed. In particular, QD solar cells are considered to hold immense potential to overcome the theoretical efficiency limit of 31% for single-junction cells.
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Affiliation(s)
- Mee Rahn Kim
- Centre-Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada
| | - Dongling Ma
- Centre-Énergie, Matériaux et Télécommunications, Institut National de la Recherche Scientifique, 1650 Boulevard Lionel-Boulet, Varennes, Québec J3X 1S2, Canada
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20
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Enhanced carrier multiplication in engineered quasi-type-II quantum dots. Nat Commun 2014; 5:4148. [PMID: 24938462 PMCID: PMC4083434 DOI: 10.1038/ncomms5148] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/16/2014] [Indexed: 01/22/2023] Open
Abstract
One process limiting the performance of solar cells is rapid cooling (thermalization) of hot carriers generated by higher-energy solar photons. In principle, the thermalization losses can be reduced by converting the kinetic energy of energetic carriers into additional electron-hole pairs via carrier multiplication (CM). While being inefficient in bulk semiconductors this process is enhanced in quantum dots, although not sufficiently high to considerably boost the power output of practical devices. Here we demonstrate that thick-shell PbSe/CdSe nanostructures can show almost a fourfold increase in the CM yield over conventional PbSe quantum dots, accompanied by a considerable reduction of the CM threshold. These structures enhance a valence-band CM channel due to effective capture of energetic holes into long-lived shell-localized states. The attainment of the regime of slowed cooling responsible for CM enhancement is indicated by the development of shell-related emission in the visible observed simultaneously with infrared emission from the core. Carrier multiplication can improve the performance of solar cells, but its efficiency is still not high enough to considerably increase the power output of practical devices. Cirloganu et al. show that appropriately designed core-shell quantum dots can enhance the carrier multiplication yield four-fold.
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Sandeep CSS, ten Cate S, Schins JM, Savenije TJ, Liu Y, Law M, Kinge S, Houtepen AJ, Siebbeles LDA. High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films. Nat Commun 2014; 4:2360. [PMID: 23974282 PMCID: PMC3759061 DOI: 10.1038/ncomms3360] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 07/26/2013] [Indexed: 11/24/2022] Open
Abstract
Carrier multiplication, the generation of multiple electron–hole pairs by a single photon, is of great interest for solar cells as it may enhance their photocurrent. This process has been shown to occur efficiently in colloidal quantum dots, however, harvesting of the generated multiple charges has proved difficult. Here we show that by tuning the charge-carrier mobility in quantum-dot films, carrier multiplication can be optimized and may show an efficiency as high as in colloidal dispersion. Our results are explained quantitatively by the competition between dissociation of multiple electron–hole pairs and Auger recombination. Above a mobility of ~1 cm2 V−1 s−1, all charges escape Auger recombination and are quantitatively converted to free charges, offering the prospect of cheap quantum-dot solar cells with efficiencies in excess of the Shockley–Queisser limit. In addition, we show that the threshold energy for carrier multiplication is reduced to twice the band gap of the quantum dots. Carrier multiplication effects are of promise for enhancement of solar cells, but have been difficult to exploit in such devices. Here, the authors demonstrate how carrier multiplication in quantum-dot films can be considerably enhanced by appropriate tuning of the charge-carrier mobility.
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Affiliation(s)
- C S Suchand Sandeep
- Optoelectronic Materials section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628BL Delft, The Netherlands
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Multiple Exciton Generation in Colloidal Nanocrystals. NANOMATERIALS 2013; 4:19-45. [PMID: 28348283 PMCID: PMC5304609 DOI: 10.3390/nano4010019] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 12/18/2013] [Accepted: 12/18/2013] [Indexed: 11/16/2022]
Abstract
In a conventional solar cell, the energy of an absorbed photon in excess of the band gap is rapidly lost as heat, and this is one of the main reasons that the theoretical efficiency is limited to ~33%. However, an alternative process, multiple exciton generation (MEG), can occur in colloidal quantum dots. Here, some or all of the excess energy is instead used to promote one or more additional electrons to the conduction band, potentially increasing the photocurrent of a solar cell and thereby its output efficiency. This review will describe the development of this field over the decade since the first experimental demonstration of multiple exciton generation, including the controversies over experimental artefacts, comparison with similar effects in bulk materials, and the underlying mechanisms. We will also describe the current state-of-the-art and outline promising directions for further development.
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Riha SC, Jin S, Baryshev SV, Thimsen E, Wiederrecht GP, Martinson ABF. Stabilizing Cu2S for photovoltaics one atomic layer at a time. ACS APPLIED MATERIALS & INTERFACES 2013; 5:10302-9. [PMID: 24147782 DOI: 10.1021/am403225e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Stabilizing Cu2S in its ideal stoichiometric form, chalcocite, is a long-standing challenge that must be met prior to its practical use in thin-film photovoltaic (PV) devices. Significant copper deficiency, which results in degenerate p-type doping, might be avoided by limiting Cu diffusion into a readily formed surface oxide and other adjacent layers. Here, we examine the extent to which PV-relevant metal-oxide over- and underlayers may stabilize Cu2S thin films with desirable semiconducting properties. After only 15 nm of TiO2 coating, Hall measurements and UV-vis-NIR spectroscopy reveal a significant suppression of free charge-carrier addition that depends strongly on the choice of deposition chemistry. Remarkably, the insertion of a single atomic layer of Al2O3 between Cu2S and TiO2 further stabilizes the active layer for at least 2 weeks, even under ambient conditions. The mechanism of this remarkable enhancement is explored by in situ microbalance and conductivity measurements. Finally, photoluminescence quenching measurements point to the potential utility of these nanolaminate stacks in solar-energy harvesting applications.
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Affiliation(s)
- Shannon C Riha
- Materials Science Division and ‡Nanoscience and Technology Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States
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