LAUSR

Cesium lead bromide (CsPbBr3) perovskite photodetectors (PDs) are attractive for applications in visible light communication (VLC) due to ultra‐high detectivity and fast response speed. However, the fabrication of high‐quality CsPbBr3 polycrystalline films using solution‐based process is very challenging. Due to the low solubility of CsBr in precursor solutions, solution‐processed CsPbBr3 films are typically discontinuous and porous, hindering the performance of resulting PDs. Herein, a facile and modified sequential spin‐coating method is introduced to prepare high‐crystallinity, pinhole‐free CsPb2Br5‐CsPbBr3 perovskite films with an average grain size of ≈1 µm. The hole‐transport‐layer‐free (HTL‐free) PDs based on the CsPb2Br5‐CsPbBr3 perovskite films show high performance parameters, including the responsivity of 0.11 A W−1, the detectivity of 1.4 × 1012 Jones, a linear dynamic range of 128.6, and an on/off ratio of 1.5 × 106. The PDs outperform other HTL‐free perovskite PDs and are comparable to the p–i–n perovskite PDs reported in the literature. In addition, the high‐performance CsPb2Br5‐CsPbBr3 PDs are applied in VLC by using the PD as a self‐powered signal receiver of voice commands in a simulated room. This work uniquely combines the features of high‐performance self‐powered perovskite PDs with VLC techniques, paving the path to wide applications of all‐inorganic perovskite PDs.