Nanometer-Thick CsPbBr3 Films with Embedded CsPb2Br5 Nanowires for Photodetector Applications

All-inorganic perovskite materials have gained enormous attention in photodetectors (PDs) due to their high charge carrier mobility, cost-effectiveness, and tunable bandgap. However, instability and corresponding performance degradation of perovskite PDs when exposed to surrounding humidity persist as challenges. In this work, a composite PD was fabricated by combining CsPb2Br5 nanowires and CsPbBr3 thin-film perovskites as an example to address these problems. The CsPb2Br5 nanowires were prepared by a facile water-bath method to improve the water resistance, and the subsequent evaporation of the CsPbBr3 film formed a type-I heterostructure to enhance its photosensitivity of PDs. As a result, the device exhibits a 10 times higher responsivity of 206 mA/W than that of the bare CsPbBr3 thin film device and maintains 92.85% of its original detectivity after being exposed to a humid environment (RH = 75%) for 144 h. Furthermore, the corresponding fundamental characterization was also performed to reveal the role of CsPb2Br5 nanowires in enhancing the overall performance of the PD. This work provides a simple and efficient approach to enhancing the durability and performance of all-inorganic halide perovskite devices through the embedding of CsPb2Br5 perovskite nanowires.