Photoelectrochemical Performance of Anatase TiO2 Thin Films Deposited by Self-Limiting Growth Techniques

Photoelectrochemical Performance of Anatase TiO2 Thin Films Deposited by Self-Limiting Growth Techniques- May 27, 2010

Fengli Wang, Nicholas G. Kubala, and Colin A. Wolden Department of Chemical Engineering, Colorado School of Mines
Anatase TiO2 photoanodes were deposited by self-limiting growth techniques at low temperature. The optical bandgap and flatband voltage of the as-deposited films agree with the values obtained from single crystal anatase. The donor density could be increased by both UV illumination and cathodic polarization in acidic solutions. Improvements in photocurrent scaled closely with changes in carrier concentration, with over 20-fold enhancements observed over the as-deposited films. The threshold potential for hydrogen intercalation was −0.6 V vs Ag/AgCl. At this level the carrier concentration could be manipulated with no change in optical transmission. At lower potentials irreversible changes are observed which are attributed to the reduction of the underlying indium tin oxide contact. In contrast, no changes were observed when fluorinated tin oxide was used as the contact layer. … All films were polycrystalline in nature, displaying the anatase signatures in both X-ray diffraction patterns and Fourier transform IR spectra. Transmission measurements on deposited films were performed using a UV/visible spectrophotometer (Stellarnet).