Fabrication of all-inorganic smart window device by cooling substrate with liquid nitrogen and study on its performance

In order to slow down the increase of substrate temperature during sputtering and then obtain electrochromic films with amorphous-porous or nano-microcrystalline structures and ion conductive film with amorphous state, a cooling facility based on liquid nitrogen, with magnetron sputtering installation has been proposed. By using the facility, a single-substrate all-inorganic electrochromic smart window device consisting of WO₃, NiO_x, and LiNbO₃ films is prepared. Its electrochromic performance has been measured by spectrophotometer, and transmittance averages of its bleached and colored states in range of 400-800 nm wavelengths have been calculated. Experimental results reveal that after 50 cycles, transmittance averages of bleached and colored states of the device have reached 61.5% and 5.5%, respectively. X-ray diffraction and SEM images show that the structures of the WO₃, NiO_x, and LiNbO₃ films are amorphous-porous, nano-microcrystalline, and amorphous states, respectively.