Photosensitization of TiO2 nanoparticulate thin film electrodes by CdS nanoparticles

Surface photovoltage spectra (SPS) measurements of TiO2 show that a large s urface state density is present on the TiO2 nanoparticles and these surface states can be efficiently decreased by sensitization using US nanoparticle s as well as by suitable heat treatment. The photoelectrochemical behavior of the bare TiO2 thin film indicates that the mechanism of photoelectron tr ansport is controlled by the trapping/detrapping properties of surface stat es within the thin films, The slow photocurrent response upon the illuminat ion can be explained by the trap saturation effect. For a TiO2 nanoparticul ate thin film sensitized using US nanoparticles, the slow photocurrent resp onse disappears and the steady-state photocurrent increases drastically, wh ich suggests that photosensitization can decrease the effect of surface sta tes on photocurrent response.