TY - JOUR
T1 - Optimizing kesterite solar cells from Cu2ZnSnS4to Cu2CdGe(S,Se)4
AU - Wexler, Robert B.
AU - Gautam, Gopalakrishnan Sai
AU - Carter, Emily A.
N1 - Funding Information:
E. A. C. thanks the U.S. Department of Energy, Office of Science, Basic Energy Sciences, under Grant DE-SC0002120 for funding this project. The authors thank Princeton Research Computing resources at Princeton University, a consortium of groups including the Princeton Institute for Computational Science and Engineering and the Princeton University Office of Information Technology's Research Computing department.
Publisher Copyright:
© The Royal Society of Chemistry 2021.
PY - 2021/4/21
Y1 - 2021/4/21
N2 - Kesterite solar cells, based on the prototypical absorber material Cu2ZnSnS4(CZTS), are cheap, nontoxic, and chemically stable, thus rendering them promising, beyond-Si photovoltaic technologies. Their efficiencies, however, are limited by the formation of defects that decrease the short-circuit current by creating deep traps where nonradiative recombination of photoexcited charge carriers occursviathe Shockley-Read-Hall mechanism. To suppress the formation of these defects, specifically the most deleterious 2CuZn+ SnZnantisite cluster, we devised an ion substitution strategy involving complete Cd- and Ge-substitution and partial selenization, ultimately arriving at the optimal composition, Cu2CdGeS3Se (CCdGSSe). Using density functional theory andab initiothermodynamics, we predict that complete Cd- and Ge-substitution leads to a 125% increase in the formation energy of the deep-trap-inducing 2CuCd+ GeCd. Additionally, 25% selenization optimizes the predicted band gap (1.43-1.47 eV, as calculated from a hybrid functional) with respect to the Shockley-Queisser limit. In addition to providing a practical and novel ion substitution strategy, we also elucidate the mechanisms of defect suppression and promotion by Ge and Se, highlighting the key role of the inert pair effect and metal-chalcogen bond covalency, respectively. Due to its ideal thermodynamic and electronic characteristics, CCdGSSe should reinvigorate research on kesterite-based solar cells, optimizing the rich materials space afforded by ion substitution and post-quinary compositions.
AB - Kesterite solar cells, based on the prototypical absorber material Cu2ZnSnS4(CZTS), are cheap, nontoxic, and chemically stable, thus rendering them promising, beyond-Si photovoltaic technologies. Their efficiencies, however, are limited by the formation of defects that decrease the short-circuit current by creating deep traps where nonradiative recombination of photoexcited charge carriers occursviathe Shockley-Read-Hall mechanism. To suppress the formation of these defects, specifically the most deleterious 2CuZn+ SnZnantisite cluster, we devised an ion substitution strategy involving complete Cd- and Ge-substitution and partial selenization, ultimately arriving at the optimal composition, Cu2CdGeS3Se (CCdGSSe). Using density functional theory andab initiothermodynamics, we predict that complete Cd- and Ge-substitution leads to a 125% increase in the formation energy of the deep-trap-inducing 2CuCd+ GeCd. Additionally, 25% selenization optimizes the predicted band gap (1.43-1.47 eV, as calculated from a hybrid functional) with respect to the Shockley-Queisser limit. In addition to providing a practical and novel ion substitution strategy, we also elucidate the mechanisms of defect suppression and promotion by Ge and Se, highlighting the key role of the inert pair effect and metal-chalcogen bond covalency, respectively. Due to its ideal thermodynamic and electronic characteristics, CCdGSSe should reinvigorate research on kesterite-based solar cells, optimizing the rich materials space afforded by ion substitution and post-quinary compositions.
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U2 - 10.1039/d0ta11603c
DO - 10.1039/d0ta11603c
M3 - Article
AN - SCOPUS:85104503431
SN - 2050-7488
VL - 9
SP - 9882
EP - 9897
JO - Journal of Materials Chemistry A
JF - Journal of Materials Chemistry A
IS - 15
ER -