Yellow tungsten oxide, also known as tungsten trioxide, is the core material for the preparation of an electrochromic device. And WO3 is present in the electrochromic layer of smart window in the form of a layer of electrochromic film. So, why the bleaching process of WO3 film takes less time than the coloring process?
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Experts explained that this is because when the ion and electron double injection tungsten trioxide electrochromic thin film is limited by the electrochromic electrode and the electrolyte interface barrier. When the ions and electrons are double-extracted, they are limited by the space charge layer in the electrochromic electrode. Due to the different limitations, a different coloring-bleaching response characteristic is created. Experts also mentioned that doping can make the structure of the film more flat, and make the color change more uniform. Also, the difference of light transmittance in the coloring-bleaching state increases, and the discoloration can be adjusted in a larger range.
