Enhanced charge transfer character of photoexcited states of dye sensitizer on the N719/TiO2 interface as revealed by electroabsorption spectra

Electroabsorption (E-A) spectra of (Bu4N)2[Ru(dcbpyH)2(NCS)2] (N719) sensitized on TiO2 nanoparticles are very different from those of the N719 solid film. In contrast with N719 fixed in a solid form, N719 adsorbed on TiO2 shows a significant electric field effect on absorbance, indicating the strong interaction in the surface between N719 and TiO2. The magnitude of the change in electric dipole moment following absorption of N719 sensitized on TiO2 is much greater than that of the sold film, suggesting that the interfacial charge transfer occurs following photoexcitation of N719 adsorbed on TiO2 surface.