Photosensitization of nanocrystalline TiO2 electrodes by squarylium cyanine incorporated with a ruthenium bipyridyl complex

Photosensitization of nanocrystalline TiO2 electrodes by adsorbing squaryli um cyanine (SQ) and a mixture of squarylium cyanine and ruthenium bipyridyl complex (RuL2(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 nanocr ystalline TiO2 electrodes was studied by absorption and infrared spectra. A n association effect of photosensitization was observed in mixtures with mo lar proportions (SQ:RuL2(NCS)(2)) of 1:20, 1:50 and 1:100 mol/mol, resultin g in the increase of the photoelectric response. Electron transfer mechanis m was suggested in terms of quenching the fluorescence of squarylium cyanin e by the presence of ruthenium bipyridyl complex and TiO2 colloids. (C) 200 0 Elsevier Science S.A. All rights reserved.