Effects of Sputtering Pressure on Electrochromic Properties of NiO films Prepared by DC Magnetron Sputtering

In this paper, nickel oxide films were deposited on ITO-coated glass substrates by DC magnetron sputtering at different pressures(1.2 Pa ∼ 3.0 Pa). The effects of sputtering pressure on microstructure and electrochromic properties of nickel oxide films were investigated. The film thickness was measured by a surface profilometer. The crystal structure and surface morphology of the films were observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochromic properties of the films were studied by combining UV-visible spectrophotometer with electrochemical workstation. The results showed that the nickel oxide film obtained the best surface morphology (uniform grain size and the fewer surface cracks) and outstanding electrochromic performances, including large transmittance modulation (ΔT = 57.19%), high coloration efficiency (CE = 33.59 cm 2 ·C −1 ) and fast switching speed (t c = 4.63 s, t b = 4.87 s) at a wavelength of 550 nm when the sputtering pressure was 2.4 Pa. And after 500 electrochemical cycles, the transmittance modulation could continue to increase to 61.49% and the coloration efficiency can still be maintained at about 28.21 cm 2 ·C −1 , which showed excellent cycling durability.