Improving the performance of Cu2ZnSn(S,Se)4 thin film solar cells by SCAPS simulation

Abstract

The effect of Se/(S + Se) ratio, absorber thickness, series and shunt resistance on Cu2ZnSn(S,Se)4 (CZTSSe) solar cells were studied by one-dimensional solar cell capacitance simulator (SCAPS-1D). The efficiency exhibited an initial increase followed by a subsequent decrease as Se/(S + Se) ratio increased, achieving peak efficiency of 17.38 % at Se/(S + Se) ratio of 0.2. As absorber thickness increased from 0.5 to 1.5 μm, both the short circuit current and efficiency exhibited continuous improvement, which was attributed to the enhanced absorption and utilization of sunlight. However, when the thickness of absorber exceeded 1.5 μm, the transport of carriers across the absorber was difficult due to the excessive thickness, and the efficiency was almost not improved. The optimal device possessed efficiency of 17.91 %. Series resistance exerted a more substantial influence on efficiency than shunt resistance. To achieve high-efficiency CZTSSe devices, series resistance should be controlled below 2 Ω·cm2, and shunt resistance should be controlled above 600 Ω·cm2.