Enhancement of electron transport in nano-porous TiO2 electrodes by dye adsorption

Influence of dye adsorption on electron transport in nano-porous TiO2 electrodes filled with electrolytes is studied with various TiO2 films and electrolytes. Electron diffusion coefficient in the electrodes is derived from pulsed laser induced current transients. It is found that dye adsorption increases the diffusion coefficients in the electrodes regardless of the difference of electrolytes and TiO2 electrodes. The degree of the increases scales with the surface area of the nano-porous electrodes. Based on trapping model, these observations can be interpreted with that the charge traps located on the electrode surface are removed by the dye adsorption. However, dependency of electron diffusion coefficients on light intensity is not affected by dye adsorption, implying that the traps are located not only on the surface but also inside the electrodes. (C) 2003 Elsevier B.V. All rights reserved.