TiO2 pore-filling and its effect on the efficiency of solid-state dye-sensitized solar cells

Solid-state dye-sensitized solar cells have been the focus of much attention over the past few years. We have recently been able to demonstrate efficiencies in excess of 4% and further improvements are expected. Here we compare a range of different hole conductor materials and investigate a number of key parameters which affect their performance. Wetting and pore-filling of the nanoporous TiO2 layer by the hole transporter appears to play a critical role in determining the final efficiency of the cell. A comparison of our results shows the importance of complete filling in contrast to just wetting of the nanoporous TiO2 layer, which is generally underestimated.