Tunable Assembly of Vanadium Dioxide Nanoparticles to Create Porous Film for Energy-Saving Applications

Nanoparticle-assembled vanadium dioxide (VO2) films have been easily prepared with the assistance of cetyltrimethylammonium vanadate (CTAV) precursor which exhibits self-assembly properties. The obtained VO2 film has a micro/nano hierarchical porous structure, so its visible-light transmittance is significantly improved (similar to 25% increased compared to continuous film). The VO2 particle density as well as the film porosity can be facilely controlled by adjusting experimental parameters such as dip-coating speed. Accordingly, film optical properties can also be tuned to a large extent, in particular the visible transmittance (T-vis) and near infrared switching efficiency (Delta T-nir). These VO2 nanoparticle-assembled films prepared by this novel method provide a useful model to research the balance between T-vis and Delta T-nir.