Preparation Of WO₃ & NiO_x Films By Electron Beam Evaporation & Research On Electrochromic Smart Window

In this thesis, the researches on electorcliromic materials were reviewed roundly, and the electrochromic mechanisms of tungsten oxide and nickel oxide films were systematically summarized. Besides these, the preparation methods and their properties and the structure of electrochromic smart window were described in detail.Tungsten oxide and nickel oxide films were prepared by electron beam evaporation method, and the effect of annealing techniques of the electrochromic properties of these films was discussed. To find the parameters of preparation and annealing process associated with the best electrochromic properties of these films, following researches and experiments were carried out: to compare the visible light transmittance of the colored state with bleaching state of the electrochromic filmswhich were annealed at different temperatures and for different duration, to count the dynamic optical density change, and to test the I-V relations of these films' electrochromic cycles and their colored/bleaching response time. While discussing the different electrochromic properties of these films, the effect of annealing on the microstructure of films was found. It was clarified that why amorphous tungsten oxide film, crystalline nickel oxide and tungsten oxide films with different crystallization exhibited different electrochromic capabilities.The semisolid-state smart window was encapsulated on the basis of the electrochromic tungsten oxide and nickel oxide films mat were obtained from the initial researches and showed the best electrochromic performances. The dynamic optical density change, the I-V relations during the electrochromic cycles, the colored/bleaching response time, and the visible light transmittance of the colored state and bleaching state of the semisolid-state smart window were investigated. The semisolid-state smart window showed perfect electrochromic performances with an obvious contrast between its colored and bleaching states. The transmittance difference at A =600nm of the semisolid-state smart window reached nearly 50%,furthermore the dynamic range of optical density change archived about 0.25-0.85. Under the applied voltage of 2V, the duration of colored process and bleaching process of the semisolid-state smart window was 2s and 1.5s respectively, which denoted rapid response velocities.Researches on the Glass/ITO/WO3/LiNbO3/NiOx/Au all solid-state smart window were referred to the effect of each film's thickness on the device's electrochromic properties. Through the test of the visible light transmittance of the colored state and bleaching state of the device, it proved good electrochromic capabilities with the dynamic optical density changed between 0.2-0.5.