Supramolecular Control of Charge-Transfer Dynamics on Dye-sensitized Nanocrystalline TiO2 Films

• Published in: Chemistry : a European journal Vol. 10; no. 3; pp. 595 - 602
• Main Authors: Hirata, Narukuni, Lagref, Jean-Jacques, Palomares, Emilio J., Durrant, James R., Nazeeruddin, M. Khaja, Gratzel, Michael, Di Censo, Davide
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 06.02.2004; WILEY‐VCH Verlag; Wiley
• Subjects: Chemistry; Chemistry, Multidisciplinary; dyes/pigments; electron transfer; Physical Sciences; ruthenium; Science & Technology; supramolecular chemistry; dyes/pigments; ruthenium; ELECTRON-TRANSFER; SOLAR-CELLS; electron transfer; INTERFACE; KINETICS; COMPLEXES; SEPARATION; supramolecular chemistry
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200305408

A [Ru(dcbpy)2(NCS)2] dye has been chemically modified by the addition of a secondary electron donor moiety, N,N‐(di‐p‐anisylamino)phenoxymethyl. Optical excitation of the modified dye adsorbed to nanocrystalline TiO2 films shows a remarkably long‐lived charge‐separated state, with a decay half time of 0.7 s. Semiempirical calculations confirm that the HOMO of the modified dye molecule is localised on the electron donor group. The retardation of the recombination dynamics relative to the unmodified control dye is caused by the increase in the spatial separation of the HOMO orbital from the TiO2 surface. The magnitude of the retardation is shown to be in agreement with that predicted from the non‐adiabatic electron‐tunnelling theory. Optimising electron‐transfer dynamics: Optical excitation of the chemically modified [Ru(dcbpy)2(NCS)2] dye adsorbed to nanocrystalline TiO2 films shows a remarkable retardation of the recombination dynamics, caused by introducing a secondary electron‐transfer function to increase the spatial separation of the HOMO from the TiO2 surface (see scheme).