Photosensitization of thin film n-ZnO electrode by an oxouranium(VI) complex in non-aqueous (acetonitrile) photoelectrochemical cell

Abstract

Spectral sensitization of semiconducting n-ZnO thin film electrode by tetramethylammonium tris(diethyldithiocarbamato)dioxouranate (VI), Me₄N[UO₂(dtc)₃], has been studied in acetonitrile medium with hydroquinone as the redox reagent. Wavelength (of light) dependence of the photocurrent has provided evidence for the sensitization effect of this complex on photocurrent. Quantum efficiency of sensitized photocurrent is found to be ~ 6% at wavelength 440 nm of monochromatic light. In the presence of the sensitizer in solution, the transient response of n-ZnO electrode to light has also been recorded in terms of open-circuit photovoltage as well as current at a fixed applied potential. Although appreciable photocurrent is observed at high anodic potential, the current-voltage (<em>J-V</em>) curve does not show any tendency of saturation in photocurrent. Long-term stability of ZnO electrode in acetonitrile medium has been tested in presence of this complex and photocurrent has been found to be almost constant up to 7h of continuous illumination, particularly at lower intensity of light (66 mW/cm²) without showing any deterioration in photoelectrode.