Highly smooth and refractive films fabricated from titanium oxide hydrate solution

Highly smooth, refractive, and transparent films have recently received attention in the fields of lighting and display applications for being used as energy saving devices via light extraction. Here, we have prepared a titanium oxide hydrate solution from titanium (IV) butoxide in N, N-dimethyl acetamide (DMAc) and evaluated inorganic films fabricated from the solution. The solution was transparent and homogenous mainly due to the complexation of titanium oxide hydrate with DMAc. The solution was spin-coated on a silicon wafer or a glass plate and dried under nitrogen to create a transparent film. The refractive index of the film was ca.1.97 at a wavelength of 550nm, even when it was annealed at a low temperature of 150°C. Atomic force microscope (AFM) results showed that the films were highly smooth and that the root-mean-square (Ra) values of the film׳s surface roughness were sub-nm scale, irrespective of the film drying condition. We identified our titanium oxide hydrate solution in DMAc as a possible good candidate material for films with a high refractive index and surface evenness.