Yellow tungsten oxide can be used to produce electrochromic film. And the prepared thin film can be used in smart windows, including building smart windows and automotive smart windows, providing solutions for building energy efficiency. The following describes a method for preparing a yellow tungsten oxide nano array electrochromic film, comprising the following steps:

Nano tungsten trioxide can be used to prepare electrochromic film. WO3 is the most studied inorganic electrochromic material, which has the advantages of pure color, stable chemical properties and strong adhesion to the substrate. However, the conventional WO3 also has the disadvantages of slow transition speed, low coloring efficiency, single color change and short cycle life.

Tungsten trioxide film has nano-clusters, nano-trees or nanowire arrays. Among them, the tungsten trioxide nanometer array electrochromic film has the advantages of large spectral adjustment range, fast response speed and long cycle life. And such thin film can be prepared by the following method.

Amorphous tungsten trioxide thin film can form larger structural voids than crystalline tungsten trioxide film with quadrangular tunnels as amorphous WO3 has irregular network structure such as pentagonal tunnels and hexagonal tunnels in addition to quadrilateral tunnels.