101
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Amani M, Taheri P, Addou R, Ahn GH, Kiriya D, Lien DH, Ager JW, Wallace RM, Javey A. Recombination Kinetics and Effects of Superacid Treatment in Sulfur- and Selenium-Based Transition Metal Dichalcogenides. NANO LETTERS 2016; 16:2786-2791. [PMID: 26978038 DOI: 10.1021/acs.nanolett.6b00536] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Optoelectronic devices based on two-dimensional (2D) materials have shown tremendous promise over the past few years; however, there are still numerous challenges that need to be overcome to enable their application in devices. These include improving their poor photoluminescence (PL) quantum yield (QY) as well as better understanding of exciton-based recombination kinetics. Recently, we developed a chemical treatment technique using an organic superacid, bis(trifluoromethane)sulfonimide (TFSI), which was shown to improve the quantum yield in MoS2 from less than 1% to over 95%. Here, we perform detailed steady-state and transient optical characterization on some of the most heavily studied direct bandgap 2D materials, specifically WS2, MoS2, WSe2, and MoSe2, over a large pump dynamic range to study the recombination mechanisms present in these materials. We then explore the effects of TFSI treatment on the PL QY and recombination kinetics for each case. Our results suggest that sulfur-based 2D materials are amenable to repair/passivation by TFSI, while the mechanism is thus far ineffective on selenium based systems. We also show that biexcitonic recombination is the dominant nonradiative pathway in these materials and that the kinetics for TFSI treated MoS2 and WS2 can be described using a simple two parameter model.
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Affiliation(s)
- Matin Amani
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Peyman Taheri
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
| | - Rafik Addou
- Department of Materials Science and Engineering, University of Texas, Dallas , Richardson, Texas 75080, United States
| | - Geun Ho Ahn
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Daisuke Kiriya
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Der-Hsien Lien
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Joel W Ager
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Robert M Wallace
- Department of Materials Science and Engineering, University of Texas, Dallas , Richardson, Texas 75080, United States
| | - Ali Javey
- Electrical Engineering and Computer Sciences, University of California , Berkeley, California 94720, United States
- Materials Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
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102
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Draguta S, Thakur S, Morozov YV, Wang Y, Manser JS, Kamat PV, Kuno M. Spatially Non-uniform Trap State Densities in Solution-Processed Hybrid Perovskite Thin Films. J Phys Chem Lett 2016; 7:715-21. [PMID: 26840877 DOI: 10.1021/acs.jpclett.5b02888] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The facile solution-processability of methylammonium lead halide (CH3NH3PbI3) perovskites has catalyzed the development of inexpensive, hybrid perovskite-based optoelectronics. It is apparent, though, that solution-processed CH3NH3PbI3 films possess local emission heterogeneities, stemming from electronic disorder in the material. Herein we investigate the spatially resolved emission properties of CH3NH3PbI3 thin films through detailed emission intensity versus excitation intensity measurements. These studies enable us to establish the existence of nonuniform trap density variations wherein regions of CH3NH3PbI3 films exhibit effective free carrier recombination while others exhibit emission dynamics strongly influenced by the presence of trap states. Such trap density variations lead to spatially varying emission quantum yields and correspondingly impact the performance of both methylammonium lead halide perovskite solar cells and other hybrid perovskite-based devices. Of additional note is that the observed spatial extent of the optical disorder extends over length scales greater than that of underlying crystalline domains, suggesting the existence of other factors, beyond grain boundary-related nonradiative recombination channels, which lead to significant intrafilm optical heterogeneities.
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Affiliation(s)
- Sergiu Draguta
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Siddharatha Thakur
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
- Nanotechnology Engineering, University of Waterloo , Waterloo, Ontario N2L 3G1, Canada
| | - Yurii V Morozov
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Yuanxing Wang
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Joseph S Manser
- Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
- Radiation Laboratory, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Prashant V Kamat
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
- Department of Chemical and Biomolecular Engineering, University of Notre Dame , Notre Dame, Indiana 46556, United States
- Radiation Laboratory, University of Notre Dame , Notre Dame, Indiana 46556, United States
| | - Masaru Kuno
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States
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104
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Park NG. Methodologies for high efficiency perovskite solar cells. NANO CONVERGENCE 2016; 3:15. [PMID: 28191425 PMCID: PMC5271566 DOI: 10.1186/s40580-016-0074-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 04/28/2016] [Indexed: 05/19/2023]
Abstract
Since the report on long-term durable solid-state perovskite solar cell in 2012, perovskite solar cells based on lead halide perovskites having organic cations such as methylammonium CH3NH3PbI3 or formamidinium HC(NH2)2PbI3 have received great attention because of superb photovoltaic performance with power conversion efficiency exceeding 22 %. In this review, emergence of perovskite solar cell is briefly introduced. Since understanding fundamentals of light absorbers is directly related to their photovoltaic performance, opto-electronic properties of organo lead halide perovskites are investigated in order to provide insight into design of higher efficiency perovskite solar cells. Since the conversion efficiency of perovskite solar cell is found to depend significantly on perovskite film quality, methodologies for fabricating high quality perovskite films are particularly emphasized, including various solution-processes and vacuum deposition method.
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Affiliation(s)
- Nam-Gyu Park
- School of Chemical Engineering and Department of Energy Science, Sungkyunkwan University (SKKU), Suwon, 440-746 Republic of Korea
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105
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Talbert EM, Zarick HF, Orfield NJ, Li W, Erwin WR, DeBra ZR, Reid KR, McDonald CP, McBride JR, Valentine J, Rosenthal SJ, Bardhan R. Interplay of structural and compositional effects on carrier recombination in mixed-halide perovskites. RSC Adv 2016. [DOI: 10.1039/c6ra16505b] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We investigate the effect of grain structure and bromide content on charge transport in methylammonium lead iodide/bromide perovskites by probing the steady-state and time-resolved photoluminescence of planar films with distinct morphologies.
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Affiliation(s)
- Eric M. Talbert
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
| | - Holly F. Zarick
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
| | | | - Wei Li
- Department of Mechanical Engineering
- Vanderbilt University
- Nashville
- USA
| | - William R. Erwin
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
| | - Zachary R. DeBra
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
| | - Kemar R. Reid
- Interdisciplinary Graduate Program in Materials Science
- Vanderbilt University
- Nashville
- USA
| | | | | | - Jason Valentine
- Department of Mechanical Engineering
- Vanderbilt University
- Nashville
- USA
| | - Sandra J. Rosenthal
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
- Department of Chemistry
| | - Rizia Bardhan
- Department of Chemical and Biomolecular Engineering
- Vanderbilt University
- Nashville
- USA
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