Vacuum-Controlled Solvent Evaporation for Morphological Engineering of Wide-Bandgap Perovskite Films

In this study, we applied the vacuum-assisted solution process (VASP), a scalable method for large-area perovskite film formation, to wide-bandgap (WBG) perovskites. The effects of various key process parameters on film morphology and quality were systematically investigated, and their impact on device performance was also analyzed. By monitoring the time-dependent chamber pressure, we revealed that faster vacuum depressurization enhances dimethylformamide evaporation, yielding larger grains and more uniform perovskite films, consistent with the LaMer nucleation model. These findings were further validated by theoretical calculations. Optimization of vacuum retention time showed that prolonged delays (>45 s) increased nucleation density, reduced N -methyl-2-pyrrolidone content in the intermediate phase, and induced wrinkled textures associated with iodide-rich domains, thereby degrading …