Efficient Near-IR Sensitization of Nanocrystalline TiO 2 Films by Zinc and Aluminum Phthalocyanines

Several zinc(II) and aluminum(III) phthalocyanines substituted by carboxylic acid and sulfonic acid groups were anchored to nanocrystalline TiO 2 films. By irradiation with visible light the photovoltaic behavior of the electrodes containing LiI / LiI 3/propylene carbonate electrolyte was measured. Most efficient results were found using zinc(II) 2,9,16,23-tetracarboxyphthalocyanine, with a current conversion efficiency at 700 nm approaching 45%. It is shown that electron injection into TiO 2 occurs from the excited singlet state of the phthalocyanine derivatives. High stability of the cell performance under continuous irradiation was found.