As an electrochromic material, WOx film can be steady-state WO3 film or metastable tungsten oxide, experts said. Well, as you may have known, there are many types of electrochromic materials, including inorganic electrochromic materials, and organic electrochromic materials, etc. The WOx film is an inorganic electrochromic film.
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Some experts have used X-ray photoelectron spectroscopy (XPS) to analyze the valence state of W element and the chemical environment of O element in the bleached state of WOx film. The results show that the film is metastable tungsten oxide when the mixed state of W6+ and W5+ exists in the colored state of the film. While the valence of W element is only W6+ in the bleached state, and the film is WO3 film with steady state. According to experts, the different valence states of tungsten ions and the different chemical environments of oxygen ions are closely related to the electrochromic mechanism of WOx films.
