Study of CZTS and CZTSSe solar cells for buffer layers selection

The output characteristics, of a thin film solar cell, are affected by several parameters related to the hetero-structure that is taken into account. In this paper, nontoxic thin film solar cells were studied. CdS/CZTS, CdS/CZTSSe, ZnS/CZTS and ZnS/CZTSSe hetero-junctions were numerically simulated using the Solar Cell Capacitance Simulator (SCAPS). According to the simulation results, we found that CdS buffer was suitable for the CZTSSe absorber and an efficiency of 9.02% was obtained. The ZnS buffer was selected for CZTS absorber and an efficiency of 8.02% has been reached. By optimizing the absorber film parameters (thickness and carrier density), we obtained conversion efficiencies as high as 9.47% and 10.00% for CdS/CZTSSe and ZnS/CZTS based solar cells respectively.