Enhanced photocurrent in thin film TiO2 electrodes prepared by sol–gel method

Abstract Thin film n-type TiO 2 electrodes of different thickness from 10 to 540 nm were prepared by the sol–gel method so as to investigate the effects of the film thickness on the photocurrent. Since a steep band gradient is expected to form in the thin film TiO 2 electrode with thickness less than the space charge layer, such steep band bending would effectively separate the photo-generated electrons and holes, leading to an increase in the photocurrent of the thin TiO 2 film electrodes. It was found that in the range of 10–540 nm in thickness, the TiO 2 film electrode of 70 nm thick showed a maximum photocurrent, which was approximately six times as large as that of the electrodes of 180–540-nm thickness. This result clearly indicates that the reduction of film thickness is effective for obtaining of the efficient n-type TiO 2 film electrode.