Tailoring Component Interaction for Air‐Processed Efficient and Stable All‐Inorganic Perovskite Photovoltaic

: All-inorganic lead halide perovskites with potential stability improvement is promising candidate for optoelectronic applications. However, fundamental questions remain over the component interaction in the perovskite precursor solution due to the limitation of the most commonly used solvents of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Here, we report a simple and very effective interaction tailoring strategy for all-inorganic CsPbI3-xBrx perovskites by involving ionic liquid solvent methylammonium acetate (MAAc). We found that C=O has strong interaction with lead (Pb2+) and the N-H…I hydrogen bonds formation are observed. The interaction enables the stable perovskite precursor solution and allows the high-quality production of pinhole-free, large grain size, and flat all-inorganic perovskite films by retarding the crystallization. With a one-step, without the necessity for antisolvent treatment, air-processing approach regardless of humidity, the corresponding photovoltaic cell exhibits a high efficiency of 17.10% along with long operation stability over 1500 h under continuous light illumination.