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Title: Ag 2ZnSn(S,Se) 4: A highly promising absorber for thin film photovoltaics

The growth in efficiency of earth-abundant kesterite Cu 2ZnSn(S,Se) 4 (CZTSSe) solar cells has slowed, due in part to the intrinsic limitations imposed by the band tailing attributed primarily to I-II antisite exchange. In this study, density functional theory simulations show that when Ag is substituted for Cu to form kesterite Ag 2ZnSnSe 4 (AZTSe), the I-II isolated antisite formation energy becomes 3.7 times greater than in CZTSSe, resulting in at least an order of magnitude reduction in I-II antisite density. Experimental evidence of an optoelectronically improved material is also provided. Comparison of the low-temperature photoluminescence (PL) structure of Cu(In,Ga)Se 2 (CIGSe), CZTSSe, and AZTSe shows that AZTSe has a shallow defect structure with emission significantly closer to the band edge than CZTSe. Existence of suppressed band tailing is found in the proximity of the room-temperature PL peak of AZTSe to its measured band gap. In conclusion, the results are consistent with AZTSe being a promising alternative to CZTSSe and CIGSe for thin film photovoltaics.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [2]
  1. Univ. of California, La Jolla, San Diego, CA (United States)
  2. IBM T.J. Watson Research Center, Yorktown Hts., NY (United States)
Publication Date:
Grant/Contract Number:
EE0006334
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 144; Journal Issue: 10; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
IBM T. J. Watson Research Center, Yorktown Heights, NY (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1470318
Alternate Identifier(s):
OSTI ID: 1241443