Solution‐Processed High‐Quality Cesium Lead Bromine Perovskite Photodetectors with High Detectivity for Application in Visible Light Communication

Abstract Cesium lead bromide (CsPbBr 3 ) 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 CsPbBr 3 polycrystalline films using solution‐based process is very challenging. Due to the low solubility of CsBr in precursor solutions, solution‐processed CsPbBr 3 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 CsPb 2 Br 5 ‐CsPbBr 3 perovskite films with an average grain size of ≈1 µm. The hole‐transport‐layer‐free (HTL‐free) PDs based on the CsPb 2 Br 5 ‐CsPbBr 3 perovskite films show high performance parameters, including the responsivity of 0.11 A W −1 , the detectivity of 1.4 × 10 12 Jones, a linear dynamic range of 128.6, and an on/off ratio of 1.5 × 10 6 . 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 CsPb 2 Br 5 ‐CsPbBr 3 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.