Efficient charge transfer process in Coumarin 153–nanotubolar TiO2 hybrid system

In this Letter the optical properties of a new hybrid electrode based on Coumarin 153 adsorbed on nanotubular TiO 2 arrays are presented. The absorbance measurements show an enlargement in the visible spectral range and the photocurrent response is sensibly increased with respect to pure TiO 2 nanostructure; moreover, the analysis of the luminescence spectra suggests the formation of Coumarin aggregates on TiO 2 surface. The mechanism of the fast injection of photoexcited electrons from the Coumarin excited levels to the TiO 2 conduction band was studied and, based on absorption, emission and photocurrent data, a strong coupling between the two components is proposed.