Spectral Sensitization of TiO2 Nanocrystalline Electrodes with Aggregated Cyanine Dyes

New chromophores were explored for use in dye-sensitized solar cells. The attachment of various di-carboxylated cyanine dyes to nanocrystalline TiO2 was examined spectroscopically and through their performance in a sensitized solar cell. It was found that aggregated forms of these cyanine dyes sensitized with an efficiency equal to that of the monomer form and that combinations of cyanine dyes could be used to sensitize solar cells over the entire visible spectrum. With the high extinction coefficients of the organic dyes, short circuit photocurrents for these cyanine-sensitized systems was maximized at a 4 μm thickness of the nanocrystalline TiO2. Short circuit photocurrents for these 4 μm solar cells were found to exceed that of ruthenium coordination complexes.