Efficient ultraviolet photodetectors based on TiO2 nanotube arrays with tailored structures

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 mu A, 10 730 and 176.3 A W-1 under the UV illumination of 350 nm (45 mu W cm(-1)) at a given bias of 2 V with TiO2 tube length of 14.7 mu m, respectively, suggesting their promising applications in efficient UV photodetectors.