Solvent-mediated crystallization and defect passivation mechanisms in ambient-air MAPbI3 films: a combined experimental and simulation study

Understanding solvent-induced crystallization and defect dynamics in hybrid perovskites is crucial for stable and high-efficiency solar cells. Here, we investigate the influence of DMF : DMSO solvent ratios on the nucleation, grain boundary passivation, and optoelectronic behaviors of MAPbI3 thin films prepared under ambient conditions. X-ray diffraction and photoluminescence analyses reveal that increasing DMSO content promotes PbI2 segregation, which passivates grain boundaries and modulates trap-assisted recombination. These structural and photophysical changes are correlated with carrier lifetimes using time-resolved photoluminescence measurements and the simulated device performance using SCAPS-1D. We find that a DMF : DMSO ratio of (6 : 4) enhances the interplay between crystalline order, the energy disorder (Urbach tail), and the charge transport. Our findings provide mechanistic insights into how solvent coordination controls defect landscapes and interface energetics in perovskite films, offering a framework for rational solvent design in ambient-stable photovoltaics.