Vibrational spectroscopic study of the coordination of (2,2′-bipyridyl-4,4′-dicarboxylic acid)ruthenium(II) complexes to the surface of nanocrystalline titania

The coordination of photosensitizing Ru(II) dyes to a nanocrystalline titania film, as employed in the Gratzel solar cell, has been examined by vibrational spectroscopy. The major infrared bands of the adsorbed dyes have been assigned by comparison with spectra (IR and Raman) of the parent dye molecules, and suggest a bidentate chelate or bridging coordination to the TiO2 surface via two carboxylate groups per dye molecule.