Surfactant templated nanoporous thin films find many applications in both conventional areas (membrane separations, low-k dielectric materials, etc.) and have the potential for many types applications (nanoarray templating, nanolithography, photovoltaics, etc.). The ability to easily obtain tunable pores and controlled pore morphology by dip or spin coating makes this synthesis method interesting in the materials synthesis community. Unlike other etching and anodization methods, the composition of the film itself can be controlled simply by the choice of inorganic precursor. Silica is the most commonly studied ceramic synthesized using surfactant templation, but the amorphous walls and electrically insulating nature of surfactant templated mesoporous silica films allows them to be used primarily in fields such as separations and low-k dielectrics. Transition metal oxides like titania which have crystalline walls, a variety of stable oxidation states, and lower electronic band gaps, are excellent alternatives for photovoltaic, catalytic and electron applications.

Non-interconnected 2D hexagonally close packed (HCP) cylindrical channels would be ideal pores for many applications because of the non-tortuous, non-intersecting path that they would offer for transport of gases, solvents, solutes, and electrons. However, the cylindrical nanopores of HCP films usually align parallel to the substrate surface because of preferential interactions between the substrate surface and the surfactant molecules. This orientation makes the pores mostly inaccessible. We have developed a straightforward method of aligned cylindrical pores in HCP silica films normal to the substrate by dip coating the films onto chemically neutral substrates. Here we extend this idea to create crystalline titania films with orthogonally oriented HCP cylindrical mesopores. Titania presents the additional challenge that crystallization, if not carefully controlled, can destroy the long range pore order introduced by the surfactant template. Controlling processing factors like humidity, curing time, and calcination temperature allows us to preserve orthogonally oriented HCP pores in crystalline titania films. Titania films with orthogonally aligned HCP nanopores have an ideal structure for organic-inorganic hybrid photovoltaics.