Structure and properties of the V-doped TiO2 thin films obtained by sol-gel and microwave-assisted sol-gel method

In the present work, TiO2 and V-doped TiO2 films with TiO2/V2O5 molar ratios 98:2 and 99.95:0.05 were prepared by sol-gel and microwave (MW) assisted sol-gel syntheses. The reagents used were tetraethyl orthotitanate, vanadyl acetylacetonate and ethanol as solvent. The solutions were prepared either by stirring for 2 h at room temperature or by exposing them for 5 min to microwaves at 300 W in an oven operated at frequency of 2.45 GHz. The deposition of the films was realized by dipcoating on microscope glass substrate. The multilayer films were obtained by successive deposition. The first benefit of using MW-assisted sol-gel preparation was the essentially increased stability of the resulted solution against gelling, behavior that is of great interest for multilayer depositions. A comprehensive structural, morphological and optical characterization of the obtained films was realized. Differences between the films obtained by the two types of preparation routes are reflected in a more compact and continuous structure with very low roughness, increased thickness and higher refractive index as well as increased transmission when MW-assisted sol-gel method was used. [GRAPHICS] .