Photoelectrochemical studies on dye-sensitized particulate ZnO thin-film photoelectrodes in nonaqueous media

For dye-sensitized solar cells, it is advantageous to use semiconductor electrodes in the form of thin particulate films (prepared from nanometer-sized colloidal particles) owing to their large surface area. The present report shows that nanocrystalline particulate ZnO thin film electrodes sensitized by rhodamine B give excellent photoresponse in nonaqueous media under visible light illumination. Even by monochromatic light (lambda = 550 nm) of low intensity (300 mu W/cm(2)), high open-circuit photopotentials up to 280 mV were generated using these electrodes. Under short-circuit conditions, the maximum incident photons to current conversion efficiency was found to be 8.5% at the peak wavelength of 555 nm in acetonitrile medium. The electrodes were found to be fairly stable in nonaqueous solvents and gave considerably high conversion efficiencies and fill factors. These relatively high efficiencies are indicative of low recombination losses in nanocrystalline particulate film electrodes.