The photoconductivity of sol-gel derived TiO2 films

TiO2 films on silica substrate were prepared by the sol-gel method. The photoconductivity of these films has been studied in different ambient conditions. The photoconductivity in vacuum is much larger than that in air. In air the photoconductivity exhibits saturation after a short illumination time. In vacuum the maximum current is reached after hours of illumination and is more than three orders of magnitude larger than in air. This effect is attributed to a loss of oxygen adsorbed at the surface. Oxygen is known as electron scavenger, and its removal extends the electron lifetime and results in a much larger saturation photocurrent. (C) 2003 Elsevier B.V. All rights reserved.