Tungsten trioxide nanoparticles may be used to prepare a smart coating, or a photochromic coating - a new environmentally friendly heat-insulation glass coating. So, why can tungsten trioxide be used to produce transparent thermal insulation coating? Or what is the principle that the tungsten trioxide thermal insulation coating can exhibit high transparency and high heat insulation performance?
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That is because tungsten trioxide nanopowder is a semiconductor material, whose forbidden band width is 2.6-2.8eV, and therefore, it has a relatively short cutoff wavelength of about 460nm. Numerous studies have shown that the surface plasmon resonance of semiconductor materials can absorb light of a specific wavelength. By performing a certain reduction treatment on the tungsten oxide nanoparticles or increasing the third-phase cations, a large amount of free electrons can be accumulated on the surface area thereof, so it has the characteristics of plasmon resonance absorption of near-infrared light. At the same time, since the particle size of nano tungsten trioxide is much smaller than the visible light wavelength, transparency to visible light can be maintained.
