Laboratoire de Photonique et des Interfaces, Ecole Polytechnique F‚d‚rale de
Lausanne
CH-1015 Lausanne, Switzerland.
Light excitation of a ruthenium complex attached to a mesoporous titanium dioxide electrode immersed into a nonaqueous electrolyte solution results in electron injection from the sensitizer into the semiconductor followed by electron transfer from a tertiary amine, either covalently linked to the sensitizer or coadsorbed on the electrode, to the oxidized dye. The oxidized amine strongly absorbs light in the 600-800nm region and is stable after extinction of the light beam indicating that long-lived charge separation is accomplished. By shifting the electrode potential close to its flatband value the reduced colorless form of the amine is regenerated, and the coloration-decoloration cycle can be repeated several times.