Co-sensitization of microporous TiO2 electrodes with dye molecules and quantum-sized semiconductor particles

The microporous titanium dioxide (TiO2) film has been prepared on a conducting glass substrate. A seven-fold enhancement in energy conversion efficiency of the dye-sensitized solar cell was achieved by pre-depositing a closely packed TiO2 thin film on the surface of the conducting glass. Moreover, FeS2 particles were coated on TiO2 electrode by chemical reaction of iron pentacarbonyl with sulfur in xylene. Both atomic force microscope (AFM) and photoelectric studies suggest that the FeS2 quantum-sized particles play a dominate role in the photoelectric conversion of FeS2/TiO2 electrode, while the FeS2 large particles have less or even no contribution to the photo-current. Furthermore, the TiO2 electrode has been co-modified with phthalocyanine dye molecules and quantum-sized semiconductor particles. Co-sensitization of the TiO2 electrode with CdSe particles and ZnTCPc dye molecules not only extends the photoresponse of CdSe/TiO2 electrode further into red region, but also improve the quantum efficiency of photoelectric conversion. We believe that such a co-sensitization technique should be of general importance in designing novel solar energy conversion devices.