Characteristic of photodiode based on vanadium oxide-TiO2 nanotubes/CH3NH3PbI3

Abstract

The aim of this study was to investigate the influence of the deposition of vanadium oxide epitaxial layer on the photoresponse of TiO2/CH3NH3PbI3 heterojunction. TiO2 nanotube array was synthesized via anodization of titanium foil at three different voltages. After annealing at 450 °C, vanadium oxide was deposited by direct deposition from vanadyl(IV) sulfate solution. Microstructure analysis has been used for the investigation of the influence of different voltages of anodization on tube diameter. Spectroscopy measurements pointed out the red shift in diffusion reflectance spectra after deposition of vanadium oxide. The presence of V5+ oxidation state has been detected on the surface of nanotube arrays by chemical analysis. CH3NH3PbI3 monocrystal was dry pressed on top of the nanotubes in order to make a photodiode. The current-voltage characteristics of the photodiode were recorded and it was observed that the sample with the smallest wall thickness and higher amount of vanadium has the best photocurrent response.