Different crystalline phases of aligned TiO₂ nanotubes and their UV photoelectric properties

Horizontally ordered arrangement TiO₂ nanotubes with various crystalline phases were prepared by electrostatic spinning, pulsed laser deposition and annealing at different temperatures. The morphology, microstructure, crystal structure and spectral absorption of the nanotubes were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and ultraviolet–visible absorption spectroscopy. Then, ordered TiO₂ nanotubes in various crystal phases were deposited to gold interdigital electrodes with a spacing of 100 μm to prepare photodetectors, and their photoelectric performance were examined and compared. The findings revealed that TiO₂ nanotubes that were annealed at 500 °C had a greater anatase content (93.8%), displayed a shorter response-recovery time (8.8 and 2.2 s, respectively) and a higher responsivity (70.2 μA/W) to UV light with a wavelength of 365 nm (optical power density of 4.9 mW/cm², bias voltage of 3 V). Finally, the UV response mechanism and advantages of horizontally ordered arrangement TiO₂ nanotubes with different crystalline phases are discussed.