Photosensitization of nanocrystalline TiO 2 electrodes by squarylium cyanine incorporated with a ruthenium bipyridyl complex

Abstract

Photosensitization of nanocrystalline TiO 2 electrodes by adsorbing squarylium cyanine (SQ) and a mixture of squarylium cyanine and ruthenium bipyridyl complex (RuL 2(NCS) 2) has been investigated. Photocurrent generation from the monomers and H-type aggregates of squarylium cyanine were observed in the action spectra of squarylium cyanine sensitized electrodes. Adsorption of mixtures of squarylium cyanine and ruthenium bipyridyl complex on nanocrystalline TiO 2 electrodes was studied by absorption and infrared spectra. An association effect of photosensitization was observed in mixtures with molar proportions (SQ:RuL 2(NCS) 2) of 1:20, 1:50 and 1:100 mol/mol, resulting in the increase of the photoelectric response. Electron transfer mechanism was suggested in terms of quenching the fluorescence of squarylium cyanine by the presence of ruthenium bipyridyl complex and TiO 2 colloids.