Improvement in photoelectric conversion of a nanostructured TiO2 electrode cosensitized with phthalocyanine and porphyrin

The cosensitization afa nanostructured titanium dioxide (TiO2) electrode with tetrasulfonated gallium phthalocyanine (0.39) and tetrasulfonated zinc porphyrin (0.61) greatly enhances thf photocurrent response in the GaTsPc Q band (640-760 nm), with sixtyfold improvement in the quantum efficiency al 700 nm, and markedly decreases the photocurrent response in the Soret band of ZnTsPP, with an eightfold drop of the quantum efficiency at 430 nm. The quantum efficiency 32.2% nt 700 nm is obtained for monochromatic illumination at 13.8 mu W . cm(-2), which presents one of the highest efficiencies reported for long wavelengths. This is attributed tit the formation of the Pc/PP heteroaggregates on the cosensitized TiO2 electrode resulting from charge-transfer interaction.