Nanocrystalline TiO2 Thin Films Fabricated Via a Polyelectrolyte Multilayer-Assisted Sol-Gel Reaction

Nanostructured anatase titanium dioxide (TiO2) thin films were fabricated with an in situ, sol-gel process in a self-assembled, polyelectrolyte multilayer (PEM) template. Because the PEM template is formed by the sequential adsorption of appositively charged, weak polyelectrolytes, polyacrylic acid, and polyallylamine, it contains nonionized carboxylic groups that are able to react with the inorganic precursor, resulting in the formation of an inorganic-organic hybrid network. After annealing, nanocrystalline TiO2 films with a controlled surface morphology, crystallite size, and a thickness on the nanometer scale were obtained. The average TiO2 crystallite size was approximately 10 nm. The surface morphology and the roughness of the nanocrystalline films were evaluated by field-emission scanning electron microscopy and atomic force microscopy. UV-vis spectroscopy was used to establish the optical parameters of the nanocrystalline TiO2 films. The as-fabricated, nanostructured TiO2 films showed high absorption in the UV region and the controlled transmission of visible light.