Time-dependent DFT study of [Fe(CN)₆]^4- sensitization of TiO₂ nanoparticles

Time-dependent DFT calculations have been performed on the absorption spectrum of [Fe(CN)₆]^4- adsorbed on a TiO2 anatase nanoparticle model to provide a detailed description of the electronic structure for this prototype system and to understand the character of the states involved in the molecule → semiconductor charge transfer process. Our results show that a direct charge injection process from an occupied dye molecular state to a nanoparticle excited state localized on a few Ti atoms, rather than to a delocalized conduction state, effectively takes place in this system, in agreement with recent experimental evidence.