Transient absorption studies of the Ru(dcbpy)(2)(NCS)(2) excited state andthe dye cation on nanocrystalline TiO2 film

We have measured dynamics of the Ru(dcbpy)(2) (NCS)(2) [dcbpy = 4,4'-dicarb oxy-2,2'-bipyridine] excited state and the dye cation on nanocrystalline Ti O2 film in the wavelength region 700-900 nm. The dye in ethanol solution an d Ru(dcbpy),(NCS), sensitized nanocrystalline Al2O3 films were used as non- injecting reference samples for excited state identification. For TiO2/Ru(d cbpy)(2)(NCS)(2) film the 'reactant' decay and 'product' formation kinetics observed at different probe wavelengths showed that the resolved transient absorption picosecond components (1.1 +/- 0.2), (12 +/- 2) and (100 +/- 5) ps are related to electron injection from the excited states of the dye to the semiconductor TiO2. (C) 2001 Elsevier Science B.V. All rights reserved .