Studies of optical absorption and electron transport in nanocrystalline TiO2 electrodes

Four kinds of nanostructured titanium dioxide (TiO2) electrodes were prepared by changing the sizes of the TiO2 nanocrystalline particles (15 urn and 27 nm in diameter) and the molecular weight (MW) of the polyethylene glycol (PEG) (MW: 20 000 and 500 000) in TiO2/water paste, which was used for sample preparation. The effects of the sizes of the TiO2 particles and MW of the PEG on the microstructure, optical absorption, photoelectrochemical current (PEC) and electron transport properties of the resultant electrodes were studied. When the size of the TiO2 nanocrystalline particles used in the paste is larger, the porosity and the sizes of the TiO2 nanocrystals produced in the resultant electrodes increases. The TiO2/water paste with different MW of the PEG has different viscosity resulting to different microstructure and electron transport property of the TiO2 electrodes. It was found that the largest PEC current intensity and best electron transport property was obtained when the TiO2 electrode was prepared with the smaller TiO2 nanocrystals (15 nm) and the PEG with MW of 500 000. (C) 2003 Elsevier Science B.V. All rights reserved.