High-performance flexible UV-photodetector via self-assembled ZnO films

Abstract

Zinc oxide (ZnO) is one of the most attractive materials for the preparation of ultraviolet photodetectors (UV PDs). However, the high leakage current and slow response speed significantly limit the practical applications of ZnO-based PDs. In this study, the fabrication of UV PDs based on self-assembled ZnO film has been proposed. The device has an ultra-low dark current (25 pA@10 V) and exhibits fast response speed (190 ms/68.6 ms) and high detectivity (1.91 × 1014 Jones) for 360 nm light. The high performance can be attributed to the operating mechanism of ‘light-induced reduction of junction barrier height’. The analysis based on the thermionic emission theory indicates that illumination can significantly reduce both the Schottky barrier height and series resistance of the device. The prepared flexible PD based on the self-assembled film not only maintains excellent detection performance but also has strong durability and mechanical robustness. After 1000 bending-recovery cycles, the flexible device exhibits excellent repeatable on/off photo-switching behaviors. The measured time-response curves of the flexible PD under five different bending states show unaffected photocurrent, demonstrating excellent flexibility and stability.