Design and optimization of highly efficient and lead-free Cs₂TeI₆-based double perovskite solar cells: Insights from DFT and SCAPS-1D

To develop and optimize lead-free Cs₂TeI₆ double perovskite solar cells, a novel integrated computational method that uses both SCAPS-1D simulations and density functional theory has been developed. The results suggested that the Cs₂TeI₆ has exceptionally favorable thermodynamic and structural characteristics which have been validated through an analysis of tolerance factor, octahedral factor, and formation enthalpies. Based on density functional theory calculations, Cs₂TeI₆ has indirect bandgap of 1.167 eV, with excellent optical absorption & dielectric properties, and a high level of stability making it a viable alternative for next-generation lead-free photovoltaic applications SCAPS-1D has been adapted to include density functional theory information so that photovoltaic characteristics can be determined for Cs₂TeI₆ perovskite solar cells. The SCAPS-1D had been adapted to incorporate the density functional theory findings to assess the photovoltaic performance of Cs₂TeI₆ perovskite solar cells. The optimization study included parameters such as absorption thickness, interface and absorber defect density, and acceptor concentration of the absorber. This study also analyzed the impact of metal work function, temperature dependence, the effect of shunt resistance and series resistance on efficiency of Cs₂TeI₆-based perovskite solar cells. The FTO/WS₂/Cs2TeI₆/Cu₂O/Carbon structure obtained a maximum efficiency of 27.41% under optimal conditions.