Thin transparent films of SnO2 semiconductor have been prepared from 3 nm diameter colloids and were used to prepare nanoparticulate electrodes. FeS2 ultra fine particles were coated on a SnO2 electrode by low temperature chemical reaction of iron pentacarbonyl with sulfur in xylene. Both the optical absorption and the photocurrent action spectrum of SnO2 electrode were extended to visible region, upon coating with FeS2 particles, by sensitization mechanism. Quantum size effect is manifested by the observation of a blue shift in both absorption and photocurrent action spectrum. PIA (Photoinduced absorption spectroscopy), where the excitation is provided by a square-wave modulated (on/off) monochromatic diode light source, is a multipurpose tool in the study of dye-sensitized solar cells. Here, we use PIA as a tool for the study of a quantum-dot modified metal oxide nanostructrued electrode. Oxidized quantum dots can easily be obtained from the spectra of transient species, and their kinetics can be explored using time-resolved techniques. Incident-Photonto-Current Efficiency about 22% has been obtained at 400 nm excitation.