Uniaxial Freezing, Freeze-Drying, and Anodization for Aligned Pore Structure in Dye-Sensitized Solar Cells

A variety of methods are available for creating the titanium dioxide (TiO₂) semiconductor surface layer of dye-sensitized solar cells (DSSCs); however, many of them are used independently to create surface morphologies that are influenced by only one process. A series of experimental techniques are utilized, some not originally used for thin film preparation, to create a semiconductor surface that exhibits variations in morphology on the macro-, micro-, and nanoscales. The techniques used to create the micro- and nanostructures are uniaxial freezing, freeze-drying, and anodization or etching, combined with the macrostructural techniques of the doctor blade method, screen printing, and/or electrophoretic deposition. When several of these techniques are used together to create, and modify, a thin film for DSSC, these techniques can produce a TiO₂ semiconductor layer for DSSC that has very high current and voltage characteristics, and a surface morphology more complex than can be created by using any one of the techniques alone.