TiO2/Eu3+ thin films with high photoluminescence emission prepared by electrophoretic deposition from nanoparticulate sols

The light emission properties of anatase TiO2/Eu3+ thin films prepared by electrophoretic deposition and of the corresponding precursor nanoparticulate sols and xerogels with different Eu3+ contents are reported. Transparent anatase TiO2 thin films were successfully obtained by electrophoretic deposition after dilution of the original sols with ethanol in order to inhibit the water hydrolysis and facilitate the drying process. The topography of the films shows a high homogeneous distribution in terms of grain size and roughness of the surface of the thin films. The film thickness varied from 50 nm to 800 nm and it was found to be strongly dependent on the Eu3+ content of the sols, probably because of uncompensated electrical charges provided by Eu3+ ions located at the surface of the nanoparticles. A spontaneous densification of the films occurs at a thickness above 400 nm and, concomitantly, a significant increase of the Eu3+ emission efficiency is detected.