Spectral sensitization of TiO2 nanocrystalline electrodes with aggregated cyanine dyes

New chromophores were explored for use in dye-sensitized solar cells. The a ttachment of various di-carboxylated cyanine dyes to nanocrystalline TiO2 w as examined spectroscopically and through their performance in a sensitized solar cell. It was found that aggregated forms of these cyanine dyes sensi tized with an efficiency equal to that of the monomer form and that combina tions of cyanine dyes could be used to sensitize solar cells over the entir e visible spectrum. With the high extinction coefficients of the organic dy es, short circuit photocurrents for these cyanine-sensitized systems was ma ximized at a 4 mum thickness of the nanocrystalline TiO2. Short circuit pho tocurrents for these 4 um solar cells were found to exceed that of rutheniu m coordination complexes.