Hot-Pressing Annealing-Induced Light Utilization Enhancement and Crystallinity Optimization Enable High-Performance Narrowband Ultraviolet Photodetectors for Real-Time Ultraviolet Radiation Monitors.

The real-time ultraviolet (UV) radiation monitor can protect personal healthcare by real-time monitoring UV radiation, highlighting the urgent need for high-performance self-powered narrowband UV detectors that can selectively response to UVA and UVB wavelengths. Existing narrowband photodetectors often rely on a surface defect-assisted charge collection narrowing strategy, which inevitably compromises device performance. In this study, a hot-pressing (HP) annealing strategy is introduced to prepare high-quality Cs3Cu2I5 films with large grains vertically spanning the entire thickness. The HP annealing reduces the defect density and light loss in the 280-375 nm range in the Cs3Cu2I5 films, and enhances the charge transport and collection in the Cs3Cu2I5/GaN heterojunction. As a result, the Cs3Cu2I5/GaN-based photodetectors achieve self-powered UV detection performance with low dark current (1.50 × 10-12 A), large responsivity (0.22 A W-1), high detectivity (6.40 × 1011 Jones), and fast response speed (26/117 µs), while maintaining narrowband detection capabilities (280-375 nm). Furthermore, the devices implement a real-time and continuous UV radiation monitor to help prevent diseases caused by excessive UV radiation. This work not only propels the evolution of high-performance narrowband UV photodetectors but also links technological innovation with equipment designed for practical applications.