Facile preparation of FTO nanocrystalline films with excellent NIR electrochromic properties by a novel chelating solution route

The selection of Low-e coated glass in the mid-latitude region has been a difficult subject. In this paper, a simple sol–gel method can be used to control the grain size of fluorine-doped tin oxide (FTO) nanocrystalline films by introducing complex chelating agents into the sols and controlling their contents. The film is a polycrystalline film with rutile structure. Through the electrochemical doping technology, the localized surface plasmonic electrochromism of FTO nanocrystals in the near infrared region (NIR) can be achieved, and the optical contrast at 1750 nm can reach 60%. The Low-e glass coated with this film can adjust dynamically the transmittance of NIR light according to people’s feelings, realize the effective control of the solar radiation heat through windows without affecting the daylight use at work time, and is suitable for using in mid-latitude zone.