Engineering Inorganic Perovskite Films by X Values of DMAPbI _x toward Large Area Photovoltaic Devices by Slot‐Die Coating

Abstract Dimethylammonium lead iodide (DMAPbI _x ) has the potential to address the phase stability issue of inorganic perovskite solar cells (PSCs). In this study, the crystallinity, phase structure, defect states, and crystal growth habits of DMAPbI _x are controlled by adjusting the x value during synthesis, where N,N‐dimethylacetamide (DMAC) is used as the solvent to regulate perovskite film growth. Furthermore, large‐area CsPbI _2.85 Br _0.15 perovskite films with preferred oriented growth are achieved using the optimized x value in DMAPbI _x through the slot‐die coating method. The inorganic PSCs, with a n‐i‐p structure and the active area of 0.04 cm ² , achieve a champion power conversion efficiency (PCE) of 19.82%, with an open‐circuit voltage ( V _oc ) of 1.16 V based on perovskite films formed by slot‐die coating. This work provides important insights into the DMAPbI _x ‐based method for fabricating high‐quality inorganic perovskite films, and paves the way for large‐area inorganic PSCs fabrication for practical applications.