Simulation study on the performance of Cu₂ZnSnS₄ thin-film solar cells by CdS-free buffer layer Zn_1−xMg_xO

The traditional CdS buffer layer in flexible CZTS solar cells leads to light absorption loss and environmental pollution. Therefore, the study of the cadmium-free buffer layer is of great significance for realizing environmentally friendly and efficient CZTS solar cells. In this paper, Zn_1−xMg_xO with an adjustable band gap and no environmental pollution is used to replace CdS. SCAPS-1D simulation software was used to analyze the effects of Zn_1−xMg_xO/CZTS heterogeneous interface band level, the carrier concentration, and the thickness of Zn_1−xMg_xO buffer layer material on the output performance of the battery. The results show that when the device structure is Mo/CZTS/Zn_0.8Mg_0.2O/n-ZnO and N_D = 10¹⁵ cm⁻³, the filling factor of the battery is the largest. When the film thickness is 350 nm, the conversion efficiency of the device is the highest, that is, the PCE is 22.5%. This scheme provides a theoretical simulation basis for further searching for a suitable CZTS cadmium-free buffer layer.