Preparation And Properties Of All Solid State WO₃ Electrochromic Device

As a kind of excellent inorganic electrochromic material, WO3 thin film shows a serial of advantages, such as low response voltage, color memory in open circuit, no blind angle, which has been widely used in large area electronic paper, tack board, energy-conservation building, etc. These features make WO3 a potential candidate toward resource and energy shortages in modern society.Chapter 1 introduces basic concept, nature, and application of WO3 thin film electrochromic device, whose crystal structure and physical-chemical characteristics are also presented. In this chapter, the preparating approach, studying progress, and future trend of WO3 thin film electrochromic device are given.Chapter 2 explains the preparation, characterization, and testing methods, that is, magnetron sputtering, X-ray diffraction (XRD), Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Four probe tester, Step profiler, Spectrophotometer.Chapter 3 prepared WO3 thin films under 1.5Pa-3.0Pa sputtering pressure by DC reactive magnetron sputtering technique. The microstructure and surface morphology were investigated from 1.5 to 3.0Pa. Furthermore, TiO2 counter electrode film and gelatinous electrolyte were prepared by RF reactive magnetron sputtering and polymerization respectively, with which WO3 thin films were assembled into solid state electrochromic devices. At last, color transformation between coloring and bleaching states were taken for each device. The coloration indicates that device achieves best performance (ΔT=63.2%) at 2.0Pa among visible light range.Chapter 4 prepared W03:N thin films by DC reactive magnetron sputtering. The structure, surface morphology, composition, and chemical bonds of WO3:N films under various N content were tested. Also, they were assembled into solid state electrochromic device with TiO2 counter electrode film and gelatinous electrolyte. The modulation properties in visible-infrared region were tested toward these devices, implying that highest modulation of 68.8% was obtained when N content was 2.80at.%.Chapter 5 discussed the design and preparation of solid state single substrate electrochromic device. Firstly, ZAO thin films of good optical and electrical properties were prepared, suggesting that it can serve as external transparent electrode layer for electrochromic device. Then, single LiPON film and single LLTO film were prepared and applied to single substrate electrochromic device, respectively. Besides, all the devices were tested under DC voltage (3V). Finally, necessary assumption and analysis were given according to the testing results.Chapter 6 summarizes the whole paper, points out the deficiencies, and predicted future research direction of WO3 film electrochromic device.