Optimization techniques for power conversion efficiency boosting in lead-free Cs2SnI4Br2-based perovskite solar cell

Lead-free perovskite solar cells (PSCs) are promising for sustainable photovoltaics; however, their performance remains below that of their lead-based counterparts. In this study, we investigate Cs2SnI4Br2 PSCs using SCAPS-1D simulations calibrated to experimental baselines and systematically optimize key design parameters. Some design recommendations are provided for lead-free Cs2SnI4Br2-based PSCs aimed at fostering sustainable and environmentally friendly photovoltaic (PV) solutions. By replacing TiO2 with tungsten disulfide as the electron-transport layer (ETL), the conduction-band offset (CBO) is tuned to a favorable + 0.18 eV, enabling suppressed recombination. The effects of tuning the metal work function of both the front and back electrodes, as well as the doping levels of the transport layers, are also investigated. The thickness and bulk defects of the absorber layer are further studied. Also, the effect of interfacial defects is investigated. Collectively, these design choices raise the simulated PCE from 2.03 % to 9.47 %. Energy loss analysis indicates that absorption remains the dominant loss mechanism. Achieving a PCE exceeding 28 % requires modifications to the optical properties of the photoactive layer, addressing one of the most critical challenges in enhancing overall device performance. These promising findings unveil the potential application of inorganic lead-free Cs2SnI4Br2-based PSCs for sustainable photovoltaic applications.