Strategy of All-Inorganic Cs₃Cu₂I₅/Si-Core/Shell Nanowire Heterojunction for Stable and Ultraviolet-Enhanced Broadband Photodetectors with Imaging Capability

In this study, for the first time, the integration of nontoxic ternary copper halide Cs3Cu2I5 with one-dimensional Si nanowires (NWs) was reported to achieve an ultraviolet (UV)-enhanced Si NW broadband photodetector. A compact and uniform coverage of Cs3Cu2I5 on the top and sidewall of Si NWs formed a core/shell heterostructure, in which Si NWs served as the growth template and the electron-Transport layer, and Cs3Cu2I5 was employed as the UV photoactive material and the hole-Transport layer. The as-fabricated Cs3Cu2I5/Si-core/shell NW photodetector demonstrates a multiband photodetection from the deep UV to near-infrared region, a fast response speed of 92.5/189.2 μs (265 nm), and a high photoresponsivity of 130 mA/W, nearly 600 times as much as the reference device constructed using Si NWs. More importantly, the proposed photodetector exhibits an excellent stability in air ambient. Typically, it could endure a high temperature of 60 °C for 11 h consecutive working; after storage in air ambient for two weeks, its photodetection ability can almost be retained. Additionally, high-resolution UV imaging applications were presented by employing the proposed photodetector as sensing pixels. These obtained results verify the effectiveness of the Cs3Cu2I5/Si-core/shell NW heterojunction strategy for UV-enhanced broadband photodetection, making such a device really possible for practical applications.