Effect on the property of the photoinduced carrier transport of CdS as sensitizer for TiO2 nanoparticulate thin films

The TiO2 nanoparticle thin films have been sensitized in situ with CdS nano particles. The SPS measurement showed that large surface state density was present on the TiO2 nanoparticles and the surface state can be efficiently decreased by sensitization as well as selecting suitable heat treatment, Bo th the photocurrent response and the charge recombination kinetics in TiO2 thin films were strongly influenced by trapping/detrapping of surface state s. The slow photocurrent response of TiO2 nanoparticulate thin films upon t he illumination was attributed to the trap saturation effects, The semicond uctor sensitization made the slow photoresponse disappeared and the steady- state photocurrent value increased drastically, which suggested that the se nsitization of TiO2 thin films with CdS could get a better charge separatio n and provide a simple alternative to minimize the effect of surface state on the photocurrent response.