wxAMPS theoretical study of the bandgap structure of CZTS thin film to improve the device performance

• Published in: Optoelectronics letters Vol. 17; no. 8; pp. 475 - 481
• Main Authors: Wang, Yanping, Wang, Jiao, Li, Haoran, Zhao, Aimei, Li, Bing, Bi, Jinlian, Li, Wei
• Format: Journal Article
• Language: English
• Published: Tianjin Tianjin University of Technology 01.08.2021; Springer Nature B.V
• Subjects: Absorbers; Carrier recombination; Copper zinc tin sulfide; Energy gap; Lasers; Optical Devices; Optics; Photonics; Photovoltaic cells; Physics; Physics and Astronomy; Solar cells; Thin films; A
• ISSN: 1673-1905; 1993-5013
• DOI: 10.1007/s11801-021-0159-6

The carrier recombination was one of the factors limiting the further improvement of the Cu 2 ZnSnS 4 (CZTS) thin film solar cells. In this paper, a proper bandgap structure was designed to solve this problem. The effects of the different bandgap structure on the CZTS thin film solar cells were studied by the solar cell performance simulation software wxAMPS. A graded bandgap structure was designed and optimized. The bandgap with a front bandgap gradient and a flat bandgap gradient had a favorable effect on the CZTS thin film solar cells. Finally, the fill factor (FF) and conversion efficiency ( η ) of the CZTS thin film solar cell were increased from 36.41% to 42.73% and from 6.85% to 10.03%, respectively. In addition, the effect of donor and acceptor defect densities in CZTS absorber layer near the CdS/CZTS interface on the device performance was studied, η of the CZTS thin film solar cell was increased from 5.99% to 7.55% when the acceptor defect concentration was 10 12 –10 13 cm −3 . Moreover, the thicknesses of the CZTS absorber layer were optimized. The FF and η of the CZTS thin film solar cell were increased to 63.41% and 15.04%, respectively.