Nano yellow tungsten oxide, which is also known as nano tungsten trioxide, may be applied for producing heat insulation coating. This type of heat-insulating coating can be applied to heat-insulating building glass and heat-insulating car window glass, which will become the mainstream of heat-insulating films in the future. It means that various studies on tungsten trioxide are needed to be done to gain insight into the characteristics of the product, such as bandgap energy.
Bandgap Energy of Tungsten Trioxide
The energy band structure of tungsten trioxide includes a low energy valence band filled with electrons, an empty high energy conduction band, and a forbidden band between them. When tungsten trioxide is given an energy greater than or equal to the band gap width, electrons (e-) in the valence band are excited, jump over the bandgap into the conduction band, and at the same time produce corresponding holes (h+) in the valence band, and therefore a highly active electron-hole pair is formed. Therefore, the size of the band gap determines the ease of electronic transitions.
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