Photocurrent transients were investigated on pressed and sintered porous TiO2 layers which were immersed in electrolyte during the measurements. Unpressed porous TiO2 layers were prepared by electrophoretic deposition. The porosity of the layers was changed systematically by pressing. The surfaces of the TiO2 nanoparticles and the intimate contact between them were identically conditioned by sintering in air at 450C after pressing. With decreasing porosity, the diffusion coefficient increased while the electron lifetime decreased. The results were explained on the basis of the change in the mean coordination number between TiO2 nanoparticles.

Influence of the Porosity on Diffusion and Lifetime in Porous TiO2 Layers. Dittrich, T., Ofir, A., Tirosh, S., Grinis, L., Zaban, A.: Applied Physics Letters , 2006, 88[18], 182110