The Preparation And Performance Research Of WO₃ Electrochromic Thin Film

Electrochromic thin films can be used for the Smart Windows, a large, high contrast, high-resolution and no-visual difference display screens, switchable car rear-view mirrors, ect.The application prospects of electrochromic thin films are very wide. It is considered to be the most promising electrochromic material because of high efficiency and good reversibility, short response time, longevity, and low cost.The topic studies e-beam deposits tungsten oxide (WO₃) target on the ITO glass. UV-visible spectrophotometer and X-ray diffraction (XRD) and atomic force microscopy (AFM) analyzes the characterization of WO3 thin films. It discusses the influence to the electrochromic properties and structure under the different parameter conditions. We find a more appropriate electrochromic film thickness and annealing temperature.The WO₃ samples were investigated by AFM. The results show that the grain size of the thin films deposited at room temperature becomes larger with the annealing temperature increased. The clusters of the thin films annealed at 350℃increased with the condition of increasing thickness or rising substrate temperature.The beam size has no significant effect on the surface morphology.Through XRD analysis of the substrate and the target it proves that the target was polycrystalline with triclinic structure. The WO₃ samples were investigated by XRD. The results show that the transformation temperature from amorphous to crystalline WO₃ thin films ranges from 320℃to 350℃. The crystalline orientation of the thin films annealed at 350℃increased with the condition of increasing thickness or rising substrate temperature.The beam size has no significant effect on the structure of crystalline.We analyze the transmittance of the thin films within the visible light after depositing thin films under room temperature and annealing at different temperatures. We compare the difference of the transmittance. We get a more appropriate thickness of the thin film and annealing conditions after the transmittance analysis of the different parameter condition thin films. Meanwhile we also study three important performance indicators switches response time, the number of recycling, memory storage capacity of the thin films.