Electron injection kinetics for the nanocrystalline TiO2 films sensitised with the dye (Bu4N)2Ru(dcbpyH)2(NCS)2

Abstract

Abstract Transient absorption spectroscopy is employed to determine the electron injection kinetics for nanocrystalline TiO2 electrodes sensitised with the dye (Bu4N)2Ru(dcbpyH)2(NCS)2 2. These kinetics are compared with control data obtained for the more widely studied fully protonated version of this with dye, Ru(dcbpyH2)2(NCS)2 1. In both cases multiphasic, ultrafast electron injection kinetics are observed. However the electron injection kinetics observed for sensitiser 2 are found to be significantly slower than sensitiser 1. Half times for electron injection are observed to be 0.4 and 12 ps with sensitisers 1 and 2, respectively. Prolonged washing of films sensitised with sensitiser 1 in non-acidified ethanol results in retardation of the kinetics, resulting in an injection half time similar to that observed for sensitiser 2. These observations are discussed in terms of the influence of the co-adsorption of protons during the sensitising process, and their relevance to photovoltaic function.