Cosensitization of a nanostructured TiO2 electrode with tetrasulfonated porphyrins and phthalocyanine

Photo - to - electric conversion of a nanostructured TiO2 electrode cosensi tized. with dye pairs of ZnTSPP - H2TSPP and ZnTSPP - GaTSPc nas investigat ed. Doping of ZnTSPP reduces self aggregation of H2TSPP and GaTSPc in the s urface of the electrode. Cosensitization markedly enhances the photoelectri c response of Q band and in the meantime greatly decreases that of Soret ba nd under monochromatic illumination. But this decrease in Soret band is off - set by the enhancement of Q band. As a result, cosensitization improves the total photo - to - electric conversion in the whole wavelength range an d creates the mixed effect in short - circuit photocurrent. The photoelectr ic behaviors of the cosensitized electrode is attributed to the presence of a low - lying charge - transfer state originating from the formation of he teroaggregates in dye pairs of ZnTSPP - H2TSPP and ZnTSPP - GaTSPc.