Influence of Cr on photoelectrochemical properties of TiO2 thin films

Both undoped and Cr-doped TiO2 thin films were investigated. The dependencies of the flat band potential on pH, Cr concentration as well as thermal reduction were determined. On the basis of the photocurrent experiments, the effect of Cr concentration and high-temperature reduction on solar energy conversion efficiency was discussed. It was found that addition of Cr leads to an increase of the recombination process of photoelectronic carriers and shifts the flat band potential towards negative values. Linear changes of the flat band potential with pH of the electrolyte has been observed for both undoped and Cr-doped films. The maximum energy conversion efficiency (above 2%) has been observed for a voltage bias of ca. 0.1-0.4 V. The highest energy conversion efficiency has been observed for undoped-TiO2 thin films. It reaches values of 1.9% and 2.2% for as sputtered and reduced samples, respectively. (C) 2003 Elsevier B.V. All rights reserved.