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

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.