Efficient ultraviolet photodetectors based on TiO2 nanotube arrays with tailored structures

Abstract

Recently, ultraviolet (UV) photodetectors based on TiO₂ semiconductors have attracted intensive attention, due to their wide applications in environmental and biological research, optical communication, astronomical investigations and missile launch detection. However, there still remain material- and fabrication-related obstacles in realizing highly efficient UV photodetectors. Here, we reported the exploration of the efficient UV photodetectors based on the highly ordered TiO₂ nanotube arrays (TNAs). The TNAs were prepared by a two-step anodic oxidation with tailored tube lengths and wall thicknesses, and then transplanted to a transparent FTO substrate to construct a front-illuminated photodetector. The as-assembled photodetectors exhibit a satisfactory stability and wavelength selectivity with a high photocurrent, photo-to-dark current ratio and responsivity up to 1395 μA, 10 730 and 176.3 A W⁻¹ under the UV illumination of 350 nm (45 μW cm⁻¹) at a given bias of 2 V with TiO₂ tube length of 14.7 μm, respectively, suggesting their promising applications in efficient UV photodetectors.