Enhancing efficiency: A study on all-inorganic CsSnBr3 metal halide perovskites with micro-band offset using DFT and SCAPS-1D modeling

In this study, we simulated a non-toxic, all-inorganic CsSnBr₃ perovskite solar cell (PSC). Using first-principles PBE functional analysis, we evaluated the optoelectronic characteristics of the CsSnBr₃ and performed numerical simulations and optimizations with SCAPS-1D. Our findings indicate that CsSnBr₃, possessing a direct band gap of 1.78 eV, represents an optimal inorganic perovskite material for PSCs. The micro-band offset (MBO) energy structure of ZnOS/CsSnBr₃/CuI, characterized by a small energy band offset, generates an intrinsic electric field (Ebi) that greatly improves carrier transport and facilitates the separation of photogenerated electron-hole pairs, resulting in a peak power conversion efficiency (PCE) of 18.89 %. Optimization of this structure involved adjusting the doping concentrations in the electron transport layer (ETL) and hole transport layer (HTL) to 10¹⁷ cm⁻³ for the ETL and 10¹⁹ cm⁻³, respectively. Increasing the absorber layer thickness improved photovoltaic characteristics, although high defect densities negatively impacted carrier diffusion length and PSC performance. Additionally, we examined the effect of varying metal back electrode (BME) and the thermal stability analysis on the PV performance of the device The micro-band offset (MBO) energy structure, as revealed by our analysis of the carrier transport pathway, enhances energy level transitions and facilitates more efficient carrier transport. Under optimal conditions, the PSCs with the MBO-energy structure demonstrated exceptional performance, with PCE = 23.98 %, Voc = 1.40 V, Jsc = 19.68 mA/cm², and FF = 86.74 %. These results highlight the significant potential of the MBO-energy structure for Sn-based PSCs. They offer valuable insights for developing stable, highly efficient, cost-effective, and environmentally friendly CsSnBr₃-based PSCs.