The mixed effect of phthalocyanine and porphyrin on the photoelectric conversion of a nanostructured TiO2 electrode

The mixed effect of tetrasulfonated gallium phthalocyanine (GaTsPc) and tetrasulfonated zinc porphyrin (ZnTsPP) on the photoelectric conversion is reported. For the liquid junction solar cell based on the cosensitized TiO2 electrode, cosensitization greatly enhances the photocurrent response at the longer wavelength (the GaTsPc Q band) and markedly decreases the photocurrent response in the Soret band of ZnTsPP. The decrease of the Soret band of ZnTsPP is offset by the improvement of the Q band of GaTsPc, resulting in the mixed effect in the short-circuit photocurrent. This is attributed to the formation of Pc/PP heteroaggregates on the cosensitized TiO2 electrode, resulting in the decreases of the concentration of GaTsPc dimer and the presence of the low-lying charge-transfer state.