Characterization and electrochromic properties of [Cu.sub.x][Ni.sub.1-x]O films prepared by sol-gel dip-coating

[Cu.sub.x][Ni.sub.1-x]O electrochromic thin films were prepared by sol-gel dip coating and characterized by XRD, UV-vis absorption and electrochromic test. XRD results show that the structure of the [Cu.sub.x][Ni.sub.1-x]O thin films is still in cubic NiO structure. UV-vis absorption spectra show that the absorption edges of the [Cu.sub.x][Ni.sub.1-x]O films can be tuned from 335 nm (x = 0) to 550 nm (x = 0.3), and the transmittance of the colored films decrease as the content of Cu increases. [Cu.sub.x][Ni.sub.1-x]O films show good electrochromic behavior, both the coloring and bleaching time for a [Cu.sub.x][Ni.sub.1-x]O film were less than 1 s, with a variation of transmittance up to 75% at the wavelength of 632.8 nm. Keywords: [Cu.sub.x][Ni.sub.1-x]O films; Electrochromic; Sol gel; Dip-coating