Design and Simulation of Single-Junction and Multi-junction Thin-Film Solar Cells Based on Copper Tin Sulfide

In this paper, single- and multi-junction thin-film solar cells based on copper tin sulfide (CTS) are proposed. The proposed single-junction cell consists of copper zinc tin sulfide (CZTS) and CTS, as a bilayer absorber. The double-junction structure is made of CZTS and CTS absorber layers for the top and bottom cells, respectively. Furthermore, a CZTS/(CZTSe)/CTS triple-junction cell, which is based on earth-abundant and non-toxic elements, is investigated. The performance of the proposed cells in the presence of tin sulfide layers as the back surface field to reduce recombination is also examined. In order to reach the maximum efficiency, the thickness of layers is varied and optimized. The simulated efficiency of the triple-junction structure, including CZTS, CZTSe, and CTS with the optimal thickness of 0.4 μm, 0.7 μm, and 0.7 μm, respectively, was as high as 34.1%.