Time-resolved experiments in dye-sensitized solar cells using [(dcbH2)2Ru(ppy)2](ClO4)2 as a nanocrystalline TiO2 sensitizer

The complex cis- [(dcbH(2))(2) Ru(ppy)(2)](2+), in which dcbH(2) is 4,4'-(CO2H)(2)-2,2'-bipyridine and ppy is 4-phenylpyridine, was anchored to nanocrystalline TiO2 films deposited onto FTO substrate. Transient UV-visible absorption spectra with the resulting electrodes were carried out in order to investigate the electron-transfer process across the excited dye/semiconductor interface, as well as the charge recombination and quenching processes. The formation of the oxidized complex [(dcbH(2))(2)Ru-III(ppy)(2)](3+) upon light excitation was monitored by transient absorption difference spectra. The compound performs successful conversion of visible light into electricity as a molecular sensitizer of nanocrystalline n-type TiO2 in photoelectrochemical solar cells. A fast quenching of the oxidized complex in the presence of iodide emphasize., the importance of a proper concentration of donor species in the redox mediator for the effective regeneration of the oxidized sensitizer. Kinetics data of electron injection obtained by time-resolved experiments are discussed in parallel with photoelectrochemical properties of the dye-sensitized anatase TiO2. (C) 2002 Published by Elsevier Science B.V.