Cosensitization of a nanostructured TiO2 electrode with tetrasulfonated gallium phthalocyanine and tetrasulfonated zinc porphyrin

The cosensitization of a nanostructured TiO2 electrode with the spectral complementary dyes, tetrasulfonated gallium phthalocyanine (GaTsPc) and tetrasulfonated zinc porphyrin (ZnTsPP), is reported. For the liquid junction cell based on a nanostructured TiO2 electrode cosensitized with GaTsPc and ZnTsPP molecules, cosensitization extends the absorbance into the region 400-750 nm, resulting in an improvement of the light harvesting efficiency and short-circuit photocurrent on illumination at 35.7 mW cm(-2). The photocurrent response at 685 nm, corresponding to the absorbance of the GaTsPc monomer, is strongly enhanced, probably due to the decrease in the surface concentration of GaTsPc molecular dimers and the possible formation of an extended ir system in GaTsPc/ZnTsPP heteroaggregates resulting from cosensitization of the electrode. (C) 1997 Elsevier Science S.A.