Analysis of Effect of Zn(O,S) Buffer Layer Properties on CZTS Solar Cell Performance Using AMPS**Supported by the Guiding Project of Strategic Emerging Industries of Fujian Provincial Department of Science and Technology under Grant No 2015H0010, the Opening Project of State Key Laboratory of High Performance Ceramics and Superfine Microstructure of Shanghai Institute of Ceramics of Chinese Academy of Sciences under

Abstract

The Cu2ZnSnS4 (CZTS)-based solar cell is numerically simulated by a one-dimensional solar cell simulation software analysis of microelectronic and photonic structures (AMPS-1D). The device structure used in the simulation is Al/ZnO:Al/nZn(O,S)/pCZTS/Mo. The primary motivation of this simulation work is to optimize the composition in the ZnO1−xSx buffer layer, which would yield higher conversion efficiency. By varying S/(S+O) ratio x, the conduction band offset (CBO) at CZTS/Zn(O,S) interface can range from −0.23 eV to 1.06 eV if the full range of the ratio is considered. The optimal CBO of 0.23 eV can be achieved when the ZnO1−xSx buffer has an S/(S+O) ratio of 0.6. The solar cell efficiency first increases with increasing sulfur content and then decreases abruptly for x > 0.6, which reaches the highest value of 17.55% by our proposed optimal sulfur content x = 0.6. Our results provide guidance in dealing with the ZnO1−xSx buffer layer deposition for high efficiency CZTS solar cells.