Multilayered High Surface Area “Brick and Mortar” Mesoporous Titania Films as Efficient Anodes in Dye-Sensitized Solar Cells

The “brick and mortar” approach is employed to synthesize thick surfactant-templated mesoporous titanium dioxide films of up to 10 μm thickness using multilayer deposition. The films exhibit very high surface areas scaling linearly with the thickness, and roughness factors of up to 1600 cm 2 /cm 2 can be reached. For the first time, surfactant-derived mesoporous titanium dioxide films of such a large thickness and surface area can be prepared without serious cracking, delamination, or deterioration of the porous structure. The mesopores are rather large (12 nm), and stacking many layers does not affect their size or accessibility, which is shown by krypton and dye adsorption experiments. Applied in dye-sensitized solar cells, the films feature a high power conversion efficiency of over 7% already at thicknesses below 4 μm due to their high surface area and dye adsorption.