ELECTRON-TRANSPORT PROPERTIES IN DYE-SENSITIZED NANOPOROUS-NANOCRYSTALLINE TIO2 FILMS

Spectral response measurements have been performed on dye-sensitized n anoporous-nanocrystalline TiO2 photoelectrodes. The effects of film th ickness, electron scavengers in the electrolyte, and surface treatment of the nanocrystalline film were studied by means of action spectra f or front- and back-side illumination. Our results show that electron a ccepters such as dioxygen and iodine strongly decrease the IPCE. Surfa ce treatment of the electrode with pyridine induces a substantial incr ease of the photocurrent yields. The observations are discussed in ter ms of kinetics at the semiconductor-electrolyte interface. IPCE values for sandwich cells were generally much higher than those obtained fro m three-electrode measurements.