The underlying synergistic mechanism of co-solvents to fabricate high-quality FAPbI 3 perovskite films

at lower thermodynamic transition temperatures, yielding high phase purity and low defect density. As a result, PSCs fabricated using this approach achieved a power conversion efficiency (PCE) of 22.80% with improved stability. The insights gained from this work provide a rational framework for solvent selection in the fabrication of high-quality perovskite films for advanced photovoltaics.