Amorphous/crystalline WO3 dual phase laminated films: Fabrication, characterization and evaluation of their electrochromic performance for smart window applications

WO 3 film possesses excellent electrochemical properties and have great potential for application in electrochromic devices. The a-WO 3 /c-WO 3 dual phase laminated film was prepared by stacking amorphous film (a-WO 3 ), made by a novel electrodeposition-assisted sol-gel method, on crystalline WO 3 film (c-WO 3 ) coated on ITO substrate. The effect of the crystal phase and electrodeposition time on the structure and the properties of a-WO 3 /c-WO 3 dual phase laminated film was investigated. The dual phase laminated film exhibited excellent electrochromic performance due to the synergistic effect of a-WO 3 and c-WO 3 , as well as the featured rougher surface of the dual phase laminated film. The thickness of a-WO 3 film gradually increased with the extension of deposition time , and a-WO 3 /c-WO 3 dual phase laminated film with appropriate thickness a-WO 3 film possessed the fastest response time and the highest optical contrast. The optimized a-WO 3 /c-WO 3 dual phase laminated film exhibited excellent electrochromic performance with high optical contrast (70.6% at 633 nm) and high coloring efficiency (53.6 cm 2  C −1 at 633 nm). Under without ion storage layer, the electrochromic device (ECD) with laminated structure dual phase a-WO 3 /c-WO 3 film as the electrochromic layer has been successfully assembled, which shows fascinating performance, providing a useful reference for the facile processing and application of electrochromic WO 3 film in smart windows .