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

Abstract Blade‐coating has emerges as a critical route for scalable manufacturing of perovskite solar cells. However, the N 2 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 PbI 2 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.