Synthesis, characterization and electrochromic properties of NiOxHy thin film prepared by a sol-gel method

In this work, sol-gel and dip-coating methods were used to produce nickel oxide/hydroxide films. Strips of glass previously coated with transparent/conducting films of SnO2 were utilized as substrates. The nickel oxide films were obtained by wetting the substrates in a solution of NiCl2. 6H(2)O in butanol and ethylene glycol. The dried gel films were found to be transparent and moisture sensitive. X-ray diffraction analysis (XRD) was performed to identify the produced compounds of heat-treated samples. A significant effect of temperature and time on the film's thickness was observed. Simultaneously, chemical analysis, e.g. carbonaceous matter and water, were examined by DSC and FTIR spectroscopy. Transmittance measurements were performed in the range of 350 nm to 850 nm in the films at different optical states. The coloration/bleaching process was found to be reversible. The cyclic voltammetry shows broad peaks related to Ni(II)/Ni(III) and Ni(III)/Ni(IV) oxidation/reduction processes. The measurements are discussed in detail in terms of the temperature effect. (C) 1998 Published by Elsevier Science B.V. All rights reserved.