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

The charge injection dynamics of dye sensitization from a surface-bound dye (coumarin 343 (C343)) to the conduction band (CB) of the TiO 2 is reported here for the first time. Ultrafast fluorescence dynamics demonstrate that the charge injection from the C343 dye to the CB of the TiO 2 occurs on a time scale of ca. 200 fs. The charge injection efficiency is attributed to strong electronic coupling between the dye and TiO 2 energy levels. The results yield a rate of injection of 5 × 10 12 s -1 .