Dye-sensitized solar cells using anodic TiO2 mesosponge: Improved efficiency by TiCl4 treatment

In the present work, we produce 15 μm thick titania mesosponge layers (TMSL) by a Ti anodization/etching process and use the layers in dye-sensitized solar cells (DSCs). We show that the solar cell efficiency can considerably be improved by a TiCl₄ hydrolysis treatment (increase of approx. 40% to an overall value of 4.9% under AM 1.5 illumination). This beneficial effect is due to the decoration of the ～10 nm wide channels present in TMSL with TiO₂ nanoparticles of approx. 3 nm diameter, which allow for a significantly higher specific dye loading of the TMS structure.