Optimized lead-free perovskite solar cell with SnS₂ ETL and Spiro-OMeTAD HTL for > 33% efficiency

This study presents the design, optimization, and simulation of a high-efficiency, lead-free perovskite solar cell structure using the SCAPS-1D simulation tool. The proposed architecture-Al/ZnO/SnS₂/CH₃NH₃SnI₃/Spiro-OMeTAD/Au leverages environmentally benign and non-toxic materials to address the pressing global demand for sustainable and green photovoltaic solutions. The simulated device achieved a remarkable power conversion efficiency (PCE) of 33.21%, with an open-circuit voltage (VOC) of 1.37 V, a short-circuit current density (JSC) of 27.35 mA/cm², and a fill factor (FF) of 88.39%. In this configuration, ZnO functions as the window layer, while SnS₂ serves as the electron transport layer (ETL). The absorber layer, CH₃NH₃SnI₃, a lead-free perovskite demonstrates optimal performance at a thickness of 0.85 μm, offering a suitable bandgap and high optical absorption. The incorporation of Spiro-OMeTAD as the hole transport layer (HTL) significantly improves charge carrier extraction and boosts efficiency from 22.77% to 33.21%. Additionally, Al and Au were selected as the optimal front and back contact materials, respectively, enhancing overall device performance through effective charge collection. Comprehensive analysis, including generation–recombination dynamics, J–V characteristics, and quantum efficiency (QE) spectra, confirms the robustness and high performance of the proposed structure. This simulation-based investigation underscores the viability of CH₃NH₃SnI₃-based lead-free perovskite solar cells as a compelling pathway toward next-generation, eco-friendly, and high-efficiency photovoltaic technologies.