Coatings in the traditional sense generally have only protective and decorative properties, which are usually unidirectional, while intelligent coatings can respond to changes in the external environment in a controlled way, and then produce adaptive special properties that allow the coating to remain effective. Nano tungsten oxide is one of the most common types of smart coatings. Its most common application is electrochromic glass, which will create an unprecedented market space in the real estate-oriented social environment.
Nano tungsten oxide is the most common intelligent coating raw material, and its advantage is electrochromic, which refers to the phenomenon that the optical properties of materials (reflectance, transmittance and absorbance) undergo reversible and stable color changes under the action of external electric field. Electrochromic materials have the advantages of low color voltage, various color changes, energy conservation and environmental protection, so they have wide application prospects in intelligent Windows, anti-glare rearview mirrors for automobiles, camouflage materials, electrochromic fabrics, information storage and detection, display and other fields.
Tungsten trioxide electrochromic glazing is mainly composed of transparent electrode, tungsten oxide electrochromic film, lithium ion electrolyte, ion storage film, transparent electrode and other five layers. In addition, a low-voltage power supply provides driving voltage to realize electrochromic of the interlayer structure. The electrochromic glazing can change color automatically, so people no longer need to hang a curtain at the window, and it can cool down in summer and keep warm in winter. In the future, it may also be possible to convert sunlight shining on the glass into electricity to meet part of the household electricity demand.
The best electrochromic material is blue tungsten oxide, which appears dark blue under the coloring state. Due to the softer color and better light insulation performance, it is suitable for daily household use. The blue tungsten oxide in crystalline state also has a high reflectance to the infrared after discoloring, which can achieve the similar thermal insulation effect to the low-radiation glass, thus helping to reduce indoor energy consumption.
However, the tungsten oxide is not perfect. Existing tungsten oxide electrochromic glass Windows have the disadvantages of short cycle life, slow response rate of electrochromic reaction of large size glass and lack of near infrared modulation capability. Therefore, most of the industrial manufacturing will improve the electrical properties of tungsten trioxide by doping other metal elements, such as titanium, molybdenum, vanadium and caesium. The addition of these elements will change the crystallinity, grain size and surface contact area of the film layer, and increase the contact area between the ionic conduction layer and the tungsten oxide layer, so as to improve the electrochromic property.
Stanford Advanced Materials supplies high-quality tungsten products to meet our customers' R&D and production needs. Please visit http://www.samaterials.com for more information.