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

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_2.85Br_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 cm², 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.