A theoretical investigation to boost the efficiency of CZTS solar cells using SCAPS-1D

Abstract

Cu2ZnSnS4 (CZTS) is predicted to be an efficient absorber than CIGS due to its cost effective, earth inabundant constituents. But, it reached a maximum experimental efficiency of 12.6% in 2013 and it remains the same for the past decade. This is due to the various crystallographic factors that limit the performance of CZTS like antisite defect formation, unfavourable band alignment with n-type CdS, etc. The major objective of this article is to identify potential strategies through which CZTS research can be pursued further using Solar Cell Capacitance Simulator (SCAPS) 1D simulator. First, it deals with understanding the difference between CZTS and its derivatives Cu2ZnSnSe4 (CZTSe) and Cu2ZnSn(SxSe1−x)4 (CZTSSe). Then, in pursuit of finding an alternative to n-CdS, the performance of various n-type semiconductors is investigated. Later, bandgap-graded structures using exponential and linear gradient laws are constructed and the performance of such structures is evaluated. Cation-substituted CZTS structures like (Ag1−xCux)2ZnSn(SxSe1−x)4(ACZTSSe) and Cu2Cd1−xZnxSn(SxSe1−x)4 (CCZTSSe) are discussed and the performance characteristics of such devices are also studied.