Hybrid Aromatic Fluoro Amine-Modified SnO₂ Electron Transport Layers in Perovskite Solar Cells for Enhanced Efficiency and Stability

SnO₂ is a widely used electron-transporting layer (ETL) in perovskite solar cells. Despite the high compatibility with the perovskite absorber layers, the presence of traps at the perovskite|SnO₂ interface results in performance losses; hence, their modification to improve the performance and stability of perovskite solar cells (PSCs) is therefore important. Herein, the SnO₂ ETL is enhanced by incorporating a bifunctional aromatic amino fluorine molecule into the SnO₂ precursor solution. The fluorine molecule is found to partially substitute the Sn and alter the energy levels while the aniline group aids in regulating the nucleation/growth rate of the perovskite crystalline films. Herein, a hole transporting material-free carbon-based PSCs (CPSCs) is fabricated. It is found that perovskite absorber layers deposited on these modified SnO₂ hybrid layers have higher optoelectronic quality, resulting in enhanced photovoltaic performance, device stability, and reduced hysteresis in CPSCs. Devices made with the modified hybrid SnO₂ layers exhibit power conversion efficiencies of 15.6% significantly better than unmodified SnO₂ with 13.5%. CPSCs with these modified SnO₂ films also exhibit remarkable retention of 88.7% of their initial PCE for a shelf-life period (ISOS-D1I) exceeding 1200 h.