ZnO Nanowires-Based Flexible UV Photodetector System for Wearable Dosimetry

This paper presents a flexible ultraviolet (UV) photodetector (PD) system based on zinc oxide (ZnO) nanowires (NWs) for wearable UV dosimetry. High-crystal quality ZnO NWs have been synthesized by chemical vapour transport technique on c-plane sapphire substrates, and thereafter, transferred and aligned at pre-defined locations on a flexible substrate using dielectrophoresis (DEP). The accurate control over DEP parameters permitted the fabrication of large-area (wafer scale) arrays of ZnO NWs-based UV PDs. Resulting PDs showed photocurrent-to-dark current ratios above 103%, fast response times (<;1 s), high sensitivity to different UV light intensities, and good stability under several UV/dark irradiation cycles. In addition, above PDs presented a robust response under extreme bending conditions, which is critical for their application in high-performance wearable UV dosimeters.