Numerical analysis and optimization of high-efficiency CZTS/CZT(SxSe1-x)4 double absorber solar cell with MoS₂ back surface field in SCAPS-1D

This paper presents the numerical analysis and band gap optimization of CZT(S x Se 1-x ) 4 in a double absorber-based thin-film solar cell to achieve higher efficiency. The proposed solar cell structure consists of 2 absorber layers, a transparent conducting oxide (TCO) made of n-SnO 2 , an n-type Zn 2 SnO 4 buffer layer, a Cd 1-y Zn y S window layer, and p-MoS 2 is used as a back surface field to enhance the performance of the modified solar cell. In this analysis, we kept the band gap of the first absorber, copper zinc tin sulfide (CZTS), at 1.5 eV and varied the band gap of the second absorber, CZT(S x Se 1-x ) 4 . The highest power conversion efficiency is obtained at a 1.317 eV band gap for Cu 2 ZnSnS 2.4 Se 1.6 absorber layer. This was accomplished by optimizing layer properties, doping densities, modifying defect densities, and adjusting the layer thickness of the proposed solar cell. For a total thickness of 1.27 μm optimized cell, we obtained the highest conversion efficiency of 35.06% for double absorber layers, with an open circuit voltage (V oc ) of 1.23 V, a short circuit current (J sc ) of 31.49 mA/cm 2 , and a fill factor of 89.86%. It is obvious from this numerical analysis that a double absorber layer of CZTS/CZT(S x Se 1-x ) 4 achieved better performance than single absorber thin film solar cells, and kesterite materials are superior as compared to CIGS and CdTe-based solar cells. • Design and optimization of a highly efficient double absorber (CZTS/CZT(S x Se 1-x ) 4 ) solar cell. • Selection of an optimal window layer of Cd 1-y Zn y S. • Incorporation of MoS 2 as a BSF to enhance the efficiency. • Investigation of CBO and VBO of the modified device structure. • Analysis of front and back contact metals of the modified solar cell.