Engineering the Morphology and Component via Multistep Deposition of CsPbBr₃ Films toward High Detectivity and Stable Self‐Powered Photodetectors

Abstract Self‐powered perovskite photodetectors (PDs) have attracted tremendous interest for their promising advantages such as fast response speed and high detectivity. However, they usually suffer from severe operating instability issues stemming from the poor film quality, impurity phase formation, and numerous surface defects. Herein, the high performance and stable self‐powered PD based on CsPbBr₃ film is demonstrated using a multistep spin‐coating method. The annealing temperature of lead bromide (PbBr₂) films and the spin‐cycles of cesium bromide (CsBr) are prioritized, which are two key factors for realizing efficient devices during multistep deposition of perovskite films. Results illustrate that these two factors affect the crystallization, covering properties, and the composition of the final film. The CsPbBr₃ film prepared from PbBr₂ treatment at 100 °C and CsBr spin‐coating for 8‐cycles has full coverage, higher phase purity, larger grain size, higher crystallinity, and fewer defects compared with the other counterparts. Therefore, the self‐powered PD based on optimized CsPbBr₃ film achieves an excellent specific detectivity of 7.01 × 10¹² Jones at 520 nm at 0 V bias voltage. In addition, 96.6% of the original photocurrent can be maintained after operating for 3600 s with 93% long‐term storage (8 weeks) in ambient air, indicating its potential applications in optoelectronics field.