Tri-iodide transport through nano-porous TiO2 networks was investigated with the aid of a structure which consisted of a nano-porous TiO2 layer which was sintered directly onto a Pt electrode and immersed in an I3-/I– electrolyte solution. At voltages below 0.3V, electronic transport in the device was dominated by catalytic reactions at the Pt/electrolyte interface. At above about 0.4V, the current flow was limited by the diffusion of tri-iodide through the nano-porous TiO2 network. By analyzing devices having various TiO2 layer thicknesses and I2 concentrations, a constant of 4.4 x 10–6cm2/s was estimated for the effective diffusion of I3- within the pores of the TiO2 network.

Diffusion Limitations to I3-/I– Electrolyte Transport Through Nanoporous TiO2 Networks. Kron, G., Rau, U., Dürr, M., Miteva, T., Nelles, G., Yasuda, A., Werner, J.H.: Electrochemical and Solid-State Letters, 2003, 6[6], E11-4