Some experts have used the TiO2 seed layer instead of WO3 seed layer to prepare the WO3 electrochromic film by hydrothermal method. Recently, research on the preparation of tungsten trioxide films by hydrothermal method or solvothermal method has focused on the improvement of hydrothermal film forming processes. Some experts have prepared an electrochromic film of tungsten trioxide by hydrothermal process with the advantages of large light modulation range and high coloring efficiency by replacing WO3 with TiO2 as the seed layer of hydrothermal growth film.

The tungsten trioxide film prepared on the FTO conductive glass has excellent photochromic property and electrochromic property. Some experts have produced such a WO3 electrochromic film. Specifically, the preparation method is as follows:

Tungsten trioxide, mainly ordered nanostructured WO3, has the characteristics of nanomaterials and outstanding quantum effects, and exhibits outstanding properties in electrophotochromic, photochromic and other optoelectronic properties. So, WO3 can be applied to conductive glass, such as, FTO conductive glass, ITO conductive glass, ITO/PET flexible conductive substrate, and conductive glass of glass and metal.

Monoclinic phase tungsten trioxide nanosheet can be used to prepare electrochromic film. The obtained WO3 film has good nanosheets morphology and less cracks. In other words, the photoelectric property of the film is good as the defects on the interface are reduced, the probability of recombination of electrons and holes is reduced, the probability of recombination of electrons and holes is reduced, and the impedance of electrons transport in the film is reduced. The following describes a method for preparing a tungsten trioxide electrochromic film which is simple in equipment, simple in operation, and capable of meeting industrial production.