Improving the synthesis of vanadium dioxide films for practical applications

Vanadium dioxide (VO₂) is a thermochromic material well-known for its fast, reversible, and sharp metal-insulator transition (MIT) near 68°C. This threshold can be further lowered through doping. This main quality makes it a prime contender for practical applications such as the optical modulation in smart windows, sensors and switches, energy-efficient thermal regulation coatings, and neuromorphic computing and electronics. 

This preliminary study evaluates electrical conductivity and optical reflectance in sol–gel-derived VO₂ thin films prepared from two precursor systems: vanadyl acetylacetonate and vanadium(V) triisopropoxide. The sols were prepared by dissolving the precursors in methanol and ethanol, respectively, at different concentrations and then deposited onto glass and silicon wafer substrates via spin coating. Hydrolysis and polycondensation of the sols were completed at ambient temperature and moisture levels, followed by thermal treatment to induce crystallization of the desired VO₂ phase. We optimize the aforementioned parameters to achieve high-purity VO₂ so that the metal–insulator transition and switching behavior can be observed during conductivity and reflectance testing.