Fabrication, characterization, and the photoelectric conversion of the nanostructured TiO2 electrode

High-surface-area TiO2 film has been deposited on an ITO conducting glass substrate from colloidal suspension. Electronic contact between particles is produced by sintering at 450 degrees C. Atomic force microscope and scanning electron microscope analyses show that the TiO2 electrode is made up of nanometer-sized and interconnected TiO2 particles and pores. The specific surface area of the TiO2 electrode is determined by the size of particles and the thickness of the film and can be measured to be 150 by the absorption spectrum study of the TiO2 electrode sensitized with zinc tetrasulfonated phthalocyanine (ZnTsPc). A liquid junction cell based on the ZnTsPc/nanostructured TiO2 electrode has been fabricated and harvests 20% of the incident solar energy flux. Under monochromatic illumination at lambda=700 nm, the incident-photon-to-current conversion efficiency is about 2.1% and the quantum efficiency, considering the actual absorption of the incident light, is 7%. The conversion efficiency reaches 1.7% under an illumination of 35 mW cm(-2), which presents one of the highest values reported for phthalocyanine photovoltaic devices. (C) 1997 American Vacuum Society.