Phosphonate-based bipyridine dyes for stable photovoltaic devices

The series of Ru(II) polypyridyl compounds shown bind to metal oxide surfaces through the phosphonic acid groups. Ground and excited state properties of the Ru(II) complexes were characterized in fluid solution and when anchored to nanocrystalline ZrO2 and TiO2 thin films. In regenerative solar cells, the complexes bound to TiO2 efficiently convert light into electricity. The position of the phosphonic acid groups on the bipyridine ligand and the introduction of a methylene spacer allow fine-tuning of the light-to-electrical energy conversion efficiencies.