The fabrication of polypyrrole–TiO2 nanorod array heterojunction with strong ultraviolet photoresponse

We prepare the heterojunction consisting of the TiO2 nanorod array and polypyrrole (PPy) by using the photoexcited TiO2 nanorod array to initiate polymerization. The structures of the heterojunction composites are investigated using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. The dependence of the charge transfer resistances of the composite films on reaction time is shown by the electrochemical impedance. Devices are prepared from the PPy–TiO2 composite films, which are synthesized in various reaction time, and photoresponse measured. The device exhibits strong photoresponse to ultraviolet lights, thus having potential as a photoconductive UV detector.