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Title: Beyond 11% efficient sulfide kesterite Cu 2Zn xCd 1–xSnS 4 solar cell: Effects of cadmium alloying

Here, kesterite Cu 2ZnSnS 4 (CZTS) thin-film solar cells have drawn worldwide attention because of outstanding performance and earth-abundant constituents. However, problems such as coexistence of complex secondary phases, the band tailing issue, short minority lifetime, bulk defects, and undesirable band alignment at p-n interfaces need to be addressed for further efficiency improvement. In this regard, Cd alloying shows promise for dealing with some of these problems. In this work, a beyond 11% efficient Cd-alloyed CZTS solar cell is achieved, and the effects of Cd-alloying and mechanism underpinning the performance improvement have been investigated. The introduction of Cd can significantly reduce the band tailing issue, which is confirmed by the reduction in the difference between the photoluminescence peak and optical band gap (E g) as well as decreased Urbach energy. The microstructure, minority lifetime, and electrical properties of CZTS absorber are greatly improved by Cd alloying. Further XPS analyses show that the partial Cd alloying slightly reduces the band gap of CZTS via elevating the valence band maximum of CZTS. This suggests that there are opportunities for further efficiency improvement by engineering the absorber and the associated interface with the buffer.
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1] ;  [3] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ;  [1]
  1. Univ. of New South Wales, Sydney, NSW (Australia)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Central South Univ., ChangSha (China)
Publication Date:
Report Number(s):
NREL/JA-5K00-68607
Journal ID: ISSN 2380-8195
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
ACS Energy Letters
Additional Journal Information:
Journal Volume: 2; Journal Issue: 4; Journal ID: ISSN 2380-8195
Publisher:
American Chemical Society (ACS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; thin film solar cells; efficiency; alloying; performance
OSTI Identifier:
1360662