Nanocomposites of titania and hybrid matrix with high refractive index

A sol–gel route for TiO₂ nanocrystals (NCs) synthesis has been developed at low temperature without surfactants. Synthetic and processing parameters have been optimized to maximize particles’ colloidal stability and crystallinity. The obtained TiO₂ NCs can be homogeneously dispersed in a sol–gel derived organic–inorganic hybrid material, resulting in homogeneous composite films when prepared by spin coating. High refractive index films were obtained with high TiO₂ NCs loading and good transparency. Furthermore, TiO₂ colloidal solutions can be used for depositing porous crystalline films, whose structural evolution has been followed under different annealing treatments. Nanocrystals were characterized by UV–Vis absorption, TEM, FT-Raman, and XRD techniques, while nanocomposite and TiO₂ films were analyzed by SEM, TEM, and spectroscopic ellipsometry.