High Quantum Yield Sensitization of Nanocrystalline Titanium Dioxide Photoelectrodes with <i>cis</i>-Dicyanobis(4,4‘-dicarboxy-2,2‘-bipyridine)osmium(II) or Tris(4,4‘-dicarboxy-2,2‘-bipyridine)osmium(II) Complexes

Abstract

Osmium polypyridyl complexes were used as sensitizers in solar cells that utilize nanocrystalline titanium dioxide photoelectrodes. Exposure of TiO 2 electrodes to sources of Os II (H 2 L‘) 2 (CN) 2 (where L‘ is 4,4‘-dicarboxylato-2,2‘-bipyridine) or Os II (H 2 L‘) 3 2+ extended the light absorption and spectral response of the cell to longer wavelengths than did exposure of TiO 2 to Ru(H 2 L‘) 2 (NCS) 2 . The Os complexes also provided very high external quantum yields for photocurrent flow and produced open-circuit voltages similar to those of the Ru complex. The Os-based systems therefore offer promise in developing efficient dye-sensitized nanocrystalline TiO 2 -based photoelectrochemical cells.