Dye-sensitized nanostructured metal oxide electrodes : Photoelectrochemical, quantum chemical and electron spectroscopic studies

Abstract: Solar cells based on dye-Sensitized nanostructured electrodes are promising for solar energy conversion. High overall light-to-energy conversion efficiencies have been obtained for systems based on TiO2 (7%) and ZnO (2%). The photocurrent losses in these electrodes have been investigated by photoelectrochemical methods. Both bare and dye-sensitized TiO2 and ZnO electrodes were studied. The measurments showed that the losses in photon to current conversion efficiency were largely dependent on the electrolyte composition and penetration depth of the light. Generally the probability of losing generated charges decreased with increased travelling distancees within the nanostructured film and with the increased concentration of electron scavengers within the electrolyte.Ruthenium polypyridine complexes are presently used as light absorbers in the dye-sensitized solar cell. The electronic structure of these dyes, and of the dyes adsorbed to nanostructured TiO2 surface was investigated by means of semiempirical quantum chemical calculations and photoelectron spectroscopy. The investigation gave insight into the electronic structure involved in the light-to-energy conversion process. To date the most efficient dyes contain bi-isonicotinic acid as attaching ligand to the nanostructured surface. A semiempirical and electron spectroscopic investigation of this ligand attached to the TiO2 rutile (110) surface was performed to investigate the molecular structure at the surface. An adsorption configuration with four equivalent oxygen bridges was proposed.