Solution-processed one-dimensional CsCu₂I₃nanowires for polarization-sensitive and flexible ultraviolet photodetectors

Recently, much progress has been made in polarization-sensitive photodetectors based on the newly-emerging metal-halide perovskites. However, compared to extensive work on visible/infrared-light photodetection, polarization-sensitive perovskite photodetectors targeted at the ultraviolet (UV) region have not been reported. In addition, most of the previously reported photodetectors concentrated on lead-halide perovskites, but the lead-toxicity and poor stability severely restricted their practical applications. In this study, for the first time, one-dimensional CsCu2I3 nanowires (NWs) were used as the light absorber to fabricate a polarization-sensitive UV photodetector because of their electric and optical anisotropy of the asymmetric structure and external morphology anisotropy, and a high photocurrent anisotropy ratio of ~3.16 was achieved. Owing to the high crystallinity of the CsCu2I3 NWs, the device exhibits remarkable photodetection ability with a photoresponsivity of ~32.3 A W-1, a specific detectivity of 1.89 × 1012 Jones, and a fast response speed of 6.94/214 µs. Moreover, such a device fabricated on a flexible substrate shows almost no photodetection degradation after extreme bending for 1000 cycles, demonstrating good flexibility and bending endurance. The results obtained highlight the great potential of such copper halides as a stable and environmentally-friendly candidate for polarization-sensitive UV photodetectors, rendering them potentially useful for assembly of optoelectronic systems in the future.