Nonvolatile and Strongly Coordinating Solvent Enables Blade-coating of Efficient FACs-based Perovskite Solar Cells

Blade-coating has emerges as a critical route for scalable manufacturing of perovskite solar cells. However, the N₂ knife-assisted blade-coating process under ambient conditions typically yields inferior-quality perovskite films due to inadequate nucleation control and disorderly rapid crystallization. To address this challenge, a novel solvent engineering strategy is developed through the substitution of N-methyl-2-pyrrolidone (NMP) with 1,3-dimethyl-1,3-diazinan-2-one (DMPU). The unique physicochemical properties of DMPU, characterized by low vapor pressure, strong coordination capability, and limited PbI₂ solubility, synergistically regulate nucleation and crystallization kinetics. This enables rapid nucleation, stabilization of intermediate phases in wet films, and controlled crystal growth, ultimately producing phase-pure perovskite films with reduced defect density. Moreover, the feasibility and superiority of the mixed solvent strategy are demonstrated. The optimized blade-coated PSCs achieve a power conversion efficiency of 21.74% with enhanced operational stability, retaining 84% initial efficiency under continuous 1-sun illumination for 1,000 h. This work provides new insights into solvent design for preparing blade-coated perovskite films.