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.