Vacuum-Assisted Perovskite Crystallization in NMP/DMF and DMSO/DMF Solvent for Large-Area Solar Modules

Vacuum-assisted crystallization is a promising strategy for large-area perovskite film formation, but the role of solvent environment in intermediate phase evolution under vacuum-assisted crystallization remains underexplored. In this work, two common mixed solvent systems—NMP/DMF and DMSO/DMF were systematically compared, aiming at investigating how their coordination characteristics affect film formation outcomes during vacuum-assisted crystallization. NMP/DMF results in a distinct intermediate phase and ultimately leads to perovskite films with uniform grains, smooth surface, lower defect densities, and enhanced optoelectronic properties compared to those obtained using DMSO/DMF. The optimized perovskite photovoltaic modules achieved a champion power conversion efficiency of 19.14% (active area: 96.5 cm 2 ). This study highlights the strong correlation between solvent coordination and crystallization behavior, providing useful insights for scalable production of high-performance perovskite modules via vacuum-assisted crystallization.