Efficient panchromatic sensitization of nanocrystalline TiO2 films by beta-diketonato ruthenium polypyridyl complexes

The beta-diketonato Ru(II)-polypyridyl complexes, Ru(4,4',4-tricarboxy-2,2':6',2-terpyridine) (1,1,1-trifluoropentane-2,4-dionato) (NCS) and Ru(4,4',4-tricarboxy-2,2':6',2-terpyridine) (1,1,1-trifluoroeicosane-2,4-dionato) (NCS), when anchored to nanocrystalline TiO2 films, achieve very efficient panchromatic sensitization over the whole visible range extending into the near IR region, yielding 70% incident photon to current conversion efficiencies (IPCE). The presence of long hydrocarbon substituents on the beta-diketonato ligand helps to prevent surface aggregation of the sensitizer.