A key process in the operation of dye-sensitized photovoltaic solar cells is the charge injection from the dye to the semi-conductor. For Ru(II)-polypyridyl dyes on TiO2, the proposed mechanism involved photoexcitation to a dye excited state, followed by electron-transfer to the semiconductor. By contrast, a direct photoexcitation occurred for [Fe(CN)6]4/-. Time dependent DFT calculations on [Ru(dcbpyH2)2(NCS)2] and [Fe(CN)6]4/- adsorbed on a TiO2 anatase nanoparticle model were presented. A detailed description of the electronic structure of these prototype systems and of the character of the excited states involved in the molecule-semiconductor charge transfer process was also presented. A direct charge injection process from an occupied dye state to a nanoparticle excited state localized on a few Ti atoms, rather than to a delocalized conduction state, took place in [Fe(CN)6]4/-, at variance with the [Ru (dcbpyH2)2(NCS)2] where electron injection took place via an indirect mechanism. This is an abstract of a paper presented at the 231st ACS National Meeting (Atlanta, GA 3/26-30/2006).
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)