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

Abstract

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 dip-coating 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.