Boosting Self-Powered Ultraviolet Photoresponse of TiO2-Based Heterostructure by Flexo-Phototronic Effects

Abstract

Ultraviolet photodetectors have long been used as key elements for various applications, including optical sensing and communication. However, accurate sensing of weak UV intensities under self-powered conditions with stable photocurrent and rapid temporal response remains critical because of challenges related to having suitable band alignment and strong junction quality. Here, an enhancement in the self-power ultraviolet (UV, λ = 365 nm) photoresponse of the silver nanowires/TiO2 Schottky photodetector is demonstrated by taking advantage of the flexoelectric phenomenon. The device does not show measurable photocurrent under self-biased conditions with low-intensity (200 µW cm–2) UV illumination, whereas a significant photocurrent of about 0.48 µA is measured by integrating the photovoltaic and flexo-phototronic effects. Additionally, rise/fall times improved from 300/1068 to 43/165 µs by utilizing the flexo-phototronic effects, depicting an enhancement of 597%. Further, remarkable responsivity of 124 mA W–1 and high detectivity of 6.5 × 1011 Jones under self-biased conditions are recorded. Moreover, microscopic evidence of flexoelectric effect modulated photoresponse is provided by photoconductive atomic force microscopy measurements. High efficiency and self-powered capability demonstrated in this study are likely to inspire the development of next-generation ultrafast, energy-efficient, and sophisticated photodetectors for communication, imaging, and sensing networks.