Synthesis of colloidal VO2 nanoparticles for thermochromic applications

Vanadium dioxide (VO2) thin films are key materials for thermochromic smart windows and commonly have a typical phase transition (insulator to metal phase) at a transition temperature of 68 °C. This research, however, found that highly crystallized VO2 nanoparticles can be successfully coated on a glass substrate with added functionalities, such as higher luminous transmittance and transition efficiency. The transition temperature revealed that the VO2 nanoparticles with post thermal treatment at 600 °C also clearly exhibited a reduced transition temperature of 69 °C in the heating curve, 59 °C in the cooling curve, and a transition width of 10 °C. By nanopatterning the thin films, we were able to prepare VO2 thin films with higher luminous transmittance than that attained with non-patterned VO2 thin films. The enhanced transition property was demonstrated using highly crystallized VO2 nanoparticles induced by post thermal treatment, and the luminous transmittance was improved by the nanopatterns on the surface of the VO2 thin films.