Synergistic Enhancement of Carrier Dynamics in Eco-Friendly Perovskite Solar Cells through Fluorinated Iodide Additive-Induced Crystallographic and Interface Modifications

This study explores advancements in tin (Sn)-based perovskite solar cells (PSCs), which face challenges compared to lead-based PSCs due to rapid crystallization kinetics and high defect densities in Sn perovskite films. To address these limitations, a synergistic strategy involving benzylamine and fluorine incorporation is employed to enhance device performance. Perovskite materials such as fluorobenzylammonium iodide (FBZAI), 2-fluorophenylethylammonium iodide (2-FPEAI), and 4-fluorooctylammonium iodide (FOEI) engineered formamidinium tin iodide (FASnI₃) are evaluated. Key photovoltaic parameters, including fill factor (FF), open-circuit voltage (Voc), short-circuit current density (Jsc), and power conversion efficiency (PCE), are analyzed. Comprehensive investigations examine the impact of absorber layer thickness, defect density, bandgap tuning, temperature, and doping concentration. The 2-FPEAI-based device with spiro-OMeTAD (2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamino)-9,9'-spirobifluorene)/2-FPEAI/C60 additives achieved a PCE of 14.65%, FF of 60.19%, Jsc of 24.325 mA/cm², and Voc of 1.0005 V. FOEI-based devices with CuI (copper iodide)/FOEI/C60 delivered a PCE of 18.51%, FF of 75.33%, Jsc of 27.31 mA/cm², and Voc of 0.899 V, while FBZAI devices showed a PCE of 16.13%, FF of 66.28%, Jsc of 26.47 mA/cm², and Voc of 0.8925 V. These findings highlight the potential of lead-free PSCs for sustainable, high-performance photovoltaic applications.