Improving the Performance of CZTS/CZTSSe Tandem Thin Film Solar Cell

Abstract

Numerical simulation of CZTS/CZTSSe tandem solar cells utilizing Silvaco-Atlas was investigated. Firstly, the performances of conventional CZTS/CdS/ZnO and CZTSSe/CdS/ZnO single solar cells with thicknesses for both absorber layers at 360 nm and 3 nm, respectively, were studied independently. A wide band gap CZTS thin-film cell and a narrow band gap CZTSSe-based cell present conversion efficiencies of 11.10% and 13.76% respectively. This agrees with experimental and simulation results previously published. Furthermore, a CZTS/CZTSe tandem cell configuration is identified keeping the identical material properties. A good conversion efficiency of 25.27% was obtained. Finally, the thickness of the CZTS adsorption layer of the top cell was optimized as a crucial factor to enhance the tandem performance. Optimal thickness coinciding to a highest efficiency of 26.05% is 420 nm. The output parameters obtained are, Jsc  28.46 mA/cm 2 , Voc  1.27 V and FF  71.83%. This suggested results may help in the future research and may lead to the fabrication of CZTSSe-based solar cells.