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Harvey SM, Houck DW, Liu W, Liu Y, Gosztola DJ, Korgel BA, Wasielewski MR, Schaller RD. Synthetic Ligand Selection Affects Stoichiometry, Carrier Dynamics, and Trapping in CuInSe 2 Nanocrystals. ACS NANO 2021; 15:19588-19599. [PMID: 34806353 DOI: 10.1021/acsnano.1c06625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
CuInSe2 nanocrystals exhibit tunable near-infrared bandgaps that bolster utility in photovoltaic applications as well as offer potential as substitutes for more toxic Cd- and Pb-based semiconductor compositions. However, they can present a variety of defect states and unusual photophysics. Here, we examine the effects of ligand composition (oleylamine, diphenylphosphine, and tributylphosphine) on carrier dynamics in these materials. Via spectroscopic measurements such as photoluminescence and transient absorption, we find that ligands present during the synthesis of CuInSe2 nanocrystals impart nonradiative electronic states which compete with radiative recombination and give rise to low photoluminescence quantum yields. We characterize the nature of these defect states (hole vs electron traps) and investigate whether they exist at the surface or interior of the nanocrystals. Carrier lifetimes are highly dependent on ligand identity where oleylamine-capped nanocrystals exhibit rapid trapping (<20 ps) followed by diphenylphosphine (<500 ps) and finally tributylphosphine (>2 ns). A majority of carrier population localizes at indium copper antisites (electrons), copper vacancies (holes), or surface traps (electrons and/or holes), all of which are nonemissive.
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Affiliation(s)
- Samantha M Harvey
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208, United States
| | - Daniel W Houck
- McKetta Department of Chemical Engineering, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Wen Liu
- McKetta Department of Chemical Engineering, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Yuzi Liu
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - David J Gosztola
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Brian A Korgel
- McKetta Department of Chemical Engineering, Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Michael R Wasielewski
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Institute for Sustainability and Energy at Northwestern, Northwestern University, Evanston, Illinois 60208, United States
| | - Richard D Schaller
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, United States
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Chugh M, Kühne TD, Mirhosseini H. Diffusion of Alkali Metals in Polycrystalline CuInSe 2 and Their Role in the Passivation of Grain Boundaries. ACS APPLIED MATERIALS & INTERFACES 2019; 11:14821-14829. [PMID: 30924332 DOI: 10.1021/acsami.9b02158] [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
The behavior of alkali atom point defects in polycrystalline CuInSe2 is studied. In this work, three grain boundary models, one coherent twin boundary and two twin boundaries with dislocation cores, are considered. Total energy calculations show that all alkali metals tend to segregate at the grain boundaries. In addition, the segregation of alkali atoms is more pronounced at the grain boundaries with the dislocation cores. The diffusion of alkali metals along and near grain boundaries is studied as well. The results show that the diffusion of alkali atoms in the grain boundary models is faster than within the bulk. In addition, the ion exchange between Na and Rb atoms at the grain boundaries leads to the Rb enrichment at the grain boundaries and the increase of the Na concentration in the bulk. While the effects of Na and Rb point defects on the electronic structure of the grain boundary with the anion-core dislocation are similar, Rb atoms passivate the grain boundary with the cation-core dislocation more effectively than Na. This can explain the further improvement of the solar cell performance after the RbF-postdeposition treatment.
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Affiliation(s)
- Manjusha Chugh
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany
| | - Thomas D Kühne
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany
| | - Hossein Mirhosseini
- Dynamics of Condensed Matter and Center for Sustainable Systems Design, Chair of Theoretical Chemistry , University of Paderborn , Warburger Str. 100 , D-33098 Paderborn , Germany
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