Stable and Sensitive Ultraviolet Photodetectors Based on High-Quality CsCu₂I₃ Films

In recent years, cesium copper(I) halides have emerged as a promising candidate for photodetection applications due to their non-toxicity, high quantum efficiency, and remarkable stability in open air. In this study, the fabrication process was optimized with an annealing treatment to achieve high-quality, pinhole-free CsCu 2 I 3 films with excellent crystallinity. The CsCu 2 I 3 photodetector (PD) exhibits an optimized UV detection performance with high responsivity, specific detectivity, and external quantum efficiency of 42 mA W –1, 1.1 × 10 11 jones, and 12.26%, respectively. Moreover, the I light / I dark ratio can reach 7.5 × 10 5, and the rise/fall times were found to be 1.49/1.33 ms. In addition, the CsCu 2 I 3 PD demonstrated excellent working stability and retained its photoresponsivity even after two months of storage in ambient air. The fabricated device is also capable of performing UV imaging. These findings highlight the great potential of lead-free CsCu 2 I 3 PD for next-generation UV optoelectronic systems.