Enhanced Electrochromic Properties of Nanostructured WO3 Film by Combination of Chemical and Physical Methods

WO3 films are the most widely used electrochromic functional layers. It is known that WO3 films prepared by pure chemical method generally possess novel nanostructures, but the adhesion between WO3 films and substrates is weak. However, WO3 films prepared by pure physical method usually show relatively dense morphology, which limits their electrochromic properties. In order to break through these bottlenecks and further improve their electrochromic properties, this work first prepared nanostructured WO3 powder by chemical method, and then using this powder as the evaporation source, nanostructured WO3 films were fabricated by vacuum thermal evaporation method. Properties of nanostructured WO3 films were systematically compared with those of ordinary WO3 films. It turned out that the nanostructured WO3 film exhibited better cyclic stability and memory effect, and also the optical modulation rate was 14% higher than that of the ordinary WO3 film. More importantly, the nanostructured WO3 film showed better adhesion with the ITO substrates. These results demonstrate that a combination of chemical and physical methods is an effective preparation method to improve the electrochromic properties of WO3 films.