Femtosecond Electron-Transfer Dynamics at a Sensitizing Dye−Semiconductor (TiO₂) Interface

Abstract

The charge injection dynamics of dye sensitization from a surface-bound dye (coumarin 343 (C343)) to the conduction band (CB) of the TiO2 is reported here for the first time. Ultrafast fluorescence dynamics demonstrate that the charge injection from the C343 dye to the CB of the TiO2 occurs on a time scale of ca. 200 fs. The charge injection efficiency is attributed to strong electronic coupling between the dye and TiO2 energy levels. The results yield a rate of injection of 5 × 1012 s-1.