Nanocrystal Technology Enhances the Lifetime of Tungsten Oxide Electrochromic Glass

Tungsten oxide electrochromic film has great application value in the field of building energy-saving glass due to its real-time adjustment of indoor lighting and thermal insulation. It is considered as the next generation energy-saving window material to replace Low-e coated glass.

 The tungsten oxide electrochromic glass window is mainly composed of a transparent electrode, a tungsten oxide electrochromic film, a lithium ion electrolyte, an ion storage film, a transparent electrode, and the like, and a low voltage power supply is provided to provide a driving voltage to realize the electricity of the sandwich structure.  It is discoloration, and the existing tungsten oxide electrochromic glazing has the disadvantages of short cycle life, slow response rate of large-sized glass electrochromic and lack of near-infrared modulation capability, which affects the wide use of the material in the field of building energy-saving glass.  

The key material affecting the electrochromic performance of the window is the tungsten oxide electrochromic film. Therefore, how to prepare the tungsten oxide electrolysis with long cycle life of electrochromic material, fast color response rate of large-sized materials and near-infrared modulation capability  The color-changing film is an urgent problem to be solved. Thus, researchers have adopted a nanocrystalline reinforced tungsten oxide electrochromic film preparation method, the specific content includes:

Take 0.9914g of tungsten chloride, 0.0477g of indium nitrate, 0.0046g of tin nitrate, dissolve it in 49.5mL of methanol, add 0.5mL of deionized water, and stir it at room temperature for 2 hours to fully dissolve, then obtain tungsten, indium,  A composite sol of tin; the obtained composite sol is uniformly coated on a transparent conductive oxide glass substrate by a dipping or spin coating technique to form a gel film, which is dried at 150 ° C for 10 minutes, and then placed in a heat treatment furnace.  The mixture was kept at 200 to 300 ° C for 1 h in an oxygen atmosphere, and then taken out, and air-cooled to room temperature to obtain a "ITO nanocrystal-WO3 amorphous" two-phase composite film.

The above research uses the nanocrystal enhancement technology to improve the electrochromic performance of the traditional tungsten oxide film in the visible light range. At the same time, the modulation of the TCO nanocrystal in the near-infrared region is used to realize the modulation of the tungsten oxide film in the near-infrared region.  The problem that the cycle life of the tungsten oxide film in the prior art is not long enough, the electrochromic response rate of the large-sized material is slow, and the near-infrared modulation capability is lacking is solved.  According to the test, the optical modulation contrast ΔT% of the tungsten oxide film in the visible light band is 70%; the optical modulation contrast ΔT% at the 1200 nm band is 50%; the color response time of the 100×100 mm2 film is 1 s, after fading treatment 2000 times. The film charge storage capacity decreased by only 3%, and its performance and lifetime were significantly improved.

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