Design and fabrication of antireflective nanoparticulate thin films with superhydrophilic self-cleaning properties on glass substrate

Design and fabrication of transparent and superhydrophilic self-cleaning thin films on glass substrate by 7 nm TiO2/22 nm SiO2 all-nanoparticle coatings via aqueous electrostatic layer-by-layer assembly processing were demonstrated in this work. Stable and conformal structure of multibilayer (TiO2/SiO2)(x) with x up to 120 was shown to exhibit antireflective, superhydrophilic, and self-cleaning multifunctional properties. This was achieved by using appropriate periodic calcinations rather than only once calcination of the assembled nanoparticulate thin films. Average refractive index of 1.30 +/- 0.03 at 633 nm and average bilayer thickness of 20.18 nm were determined for the as-fabricated nanoparticulate thin films. Furthermore, average transmittance values higher than 93.5% were exhibited by all the nanoparticulate thin films and the experimental results were only at the very most of 2% lower than those predicted by the theory. The self-cleaning properties of the nanoparticulate thin films were revealed by the decomposition of two model contaminants under UV illumination. The experimental results showed that the photocatalytic decomposition rates are increased with the increase of bilayer number of the nanoparticulate thin film. (C) 2011 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.