Detailed experimental and theoretical investigation of the electron transport in a dye solar cell by means of a three-electrode configuration

Dye solar cells, have been built in a three-electrode configuration where the nanoporous TiO2 layer has been contacted additionally on the rear side by means of a thin porous layer of metal titanium. With this third electrode, it was proved that under short-circuit conditions and an illumination intensity equivalent to 1 sun, the differences of the electrochemical potential of the electrons between the two ends of the TiO2 layer reached values of more than 600 meV. The results confirm our former work carried out using an indirect method. As the third electrode could be used as a current collector as well, deeper insight in the transient behavior was achieved. A model has been developed to describe the transient electron transport through the TiO2 matrix, taking explicitly into account the numerous trap states of nanoporous anatase. The model turned out to be in good agreement with the experimental results.