Since Deb's experiment in 1973 on the electrochromic effect, transmissive electrochromic films exhibit outstanding
potential as energy efficient window controls which allow dynamic control of the solar energy transmission. These
films with non-volatile memory, once in the coloured state, remain in the same state even after removal of the field. The
optical and electrochemical properties of electrochromic films using magnetron sputter deposition tungsten oxide thin
films and vanadium oxide doped tungsten-vanadium oxide thin films on ITO coated glass were investigated. From the
UV region of the transmittance spectra, the optical band gap energy from the fundamental absorption edge can be
determined. And the Cyclic voltammograms of these thin films in 1 mol LiClO<sub>4</sub> propylene carbonate electrolyte (LIPC)
were measured and analysed. The anode electrochromic V<sub>2</sub>O<sub>5</sub> doped cathode electrochromic WO<sub>3</sub> could make films colour changing while the transmittance of films keeped invariance. These performance characteristics make tungstenvanadium
oxide colour changeably thin films are suitable for electrochromic windows applications.
In the present investigation, the electrochromic properties of a protonic solid state device: WO<sub>3</sub> / Ta<sub>2</sub>O<sub>5</sub> / NiO<sub>x</sub> prepared
at room temperature (300K) is reported. The non-stoichiometric tungsten oxide thin film (100nm), the tantalum oxide
thin film (360nm) and the nickel oxide thin film (50nm) are prepared by RF magnetron sputtering technique on ITO
coated glass; The transmittance variation for Li<sup>+</sup> device is +30% and for Ta<sup>+</sup> device is -2%. The optical band gap for
WO3 film is 3.11eV, for WO<sub>3</sub> / Ta<sub>2</sub>O<sub>5</sub> / NiO<sub>x</sub> multilayer films is 2.98eV.
The electrochromic effect, change of optical transmittance with respect to the applied DC voltage,is a well-known phenomenon. The electrochromic film can be fabricated with various methods such as rf and dc sputtering, chemical vapour deposition, electron, thermal and ion cluster beams and several other methods. Sol-gel process offeres several advantages over conventional deposition method for the control of stoichiometry and film structure. It was known that WO<sub>3</sub> thin film doped with niobium and with Lithium exhibits a well bleaching process as compared with pure tungsten oxide film <sup>[1-4]</sup>. The presence of Li, Ta, Ti and Nb in WO<sub>3</sub> film improves the spectroelectrochemical response of these materials. So in this paper, we presented a mixed-metal oxide sol-gel synthesis, deposition, optical and electrochromic performances of Nickel (II) acetate doped tungsten molybdenum oxide film WO<sub>3</sub>-MoO<sub>3</sub>--Ni(CH<sub>3</sub>COO)<sub>2</sub>. The range of dopant concentration was 0.75ml-7.5ml V%. Film made from WO<sub>3</sub>-MoO<sub>3</sub> precursor solutions was also used for comparison. The film has been studied and characterized by ultraviolet-visible spectroscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM) and electrochemistric station. The good coloring and bleaching behaviors of doped Ni film mean that they are suitable for electrochromic material.