WO3 can be prepared into a WO3 film, and then be applied for the production of a new electrochromic device. Wherein, the WO3 electrochromic film is the typical representative of the earliest and most studied cathode electrochromic material.

Tungsten trioxide is a typical cathode electrochromic material for preparing WO3 film, which has the advantages of large light modulation range, high color change efficiency and good cycle reversibility, so it can be used for producing a new electrochromic device. Wherein, WO3 and WO3 electrochromic film have been extensively studied.

WO3 powder has always been the most fully studied electrochromic material. However, there are still many problems in the preparation and practical application of large-area WO3 electrochromic thin films for assembling a large area electrochromic device. In other words, the production of large-area WO3 electrochromic devices and its promotion of practical applications still have a long way to go.

Tungsten trioxide powder may be used to study or assemble a large area electrochromic device such as a smart window (an energy-saving glass), to regulate the transmission of light, thereby reducing the cooling energy consumption of buildings. It is reported that such smart glass is in line with international environmental protection and energy conversation. Also, as the theme of environmental protection and energy conversation is deeply concerned by the public, the smart device of tungsten trioxide film will have a wide application.