Impact of Hole Transport Layers in Inorganic Lead-Free CsSnI₃ Perovskite Solar Cells: A Numerical Analysis

Tin-based halide perovskite compounds have attracted enormous interest as effective replacement to the conventional lead halide perovskite solar cells (PCSs). However, getting high efficiency for tin-based perovskite solar cells is still challenging. Herein, we demonstrate lead free tin-based CsSnI₃ perovskite solar cells with introducing CuS as hole transport material to enhance the photovoltaic performance of the designed CsSnI₃ perovskite solar cell. The CuS hole transport layer (HTL) with proper band structure can notably minimize the charge carrier recombination at the back side of the perovskite. In this study, lead free tin-based CsSnI₃ perovskite solar cell structure consisting of CuS/CsSnI₃/TiO₂/ITO has been carried out using SCAPS-1D. The characteristics of the proposed device is numerically evaluated by varying the thickness, doping concentration, bulk defect density of the absorber layer. In addition, DFT-extracted physical parameters including band gap, the absorption spectrum of CuS are used in the SCAPS-1D to analyze the characteristics of the proposed solar cell device. Furthermore, different HTMs are further investigated to observe the characteristics of the proposed CsSnI₃ perovskite solar cell. The power conversion efficiency (PCE) of ~29% is achieved with open circuit voltage (V_oc) of 0.99 V, fill factor of ~87%, and short circuit current density (J_sc) of 33.49 mA/cm² for the optimized device. This works addresses a proper guideline and introduces a convenient approach to design and fabricate highly efficient and stable lead free tin-based perovskite solar cells with lower cost.