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 (TiO 2 ) 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 TiO 2 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.