To improve the electrochromic properties of WO3 thin films,polyethylene glycol (PEG)-modified WO3 films via Sol-Gel method were prepared on indium-tin oxide (ITO) glass using dipping-coating technique with post annealing treatment in air.Crystal structures and morphologies of the as-prepared films were investigated by means of X-ray diffraction (XRD) and scanning electron microscope (SEM).Optical properties and cyclic voltage-current characteristic of the films were experimentally studied.Compared with the corresponding neat WO3 films,the PEG-modified WO3 films exhibit superior electrochromic properties,which possesses longer lifetime after 5000 cycles without obvious degradation,as well as higher optical modulation up to 71％ at the wavelength of 633 nm.The results suggest that PEG addition in conjunction with post annealing treatment may change the micro-structure of WO3 films to increase the electrochromic properties,due to the enhancement of ion diffusion capacity in the electrochromic material,as evident from the formation of the porous structure with an average pore diameter of 9 nm.As cycling stability is very crucial for practical applications of electrochromic materials,particularly for smart windows,this research provides a promising low-cost wet-chemical route to high performance WO3-based electrochromic devices.%为改善WO3薄膜的电致变色性能,采用溶胶-凝胶法制备了聚乙二醇(PEG)改性的WO3电致变色薄膜,并对其着色态与漂白态的光学特性以及循环伏安特性进行了研究.研究表明:PEG改性的WO3薄膜具有良好的电致变色性能,循环5000次伏安曲线无明显衰减,对可见光的最大透过率调制幅度可达71％.PEG的加入改变了WO3薄膜的微结构,形成了平均直径为9 nm的介孔,提高了离子在其中的扩散速率,因此改善了WO3薄膜的电致变色性能.由于循环稳定性对于电致变色材料的实际应用至关重要,因此这种低成本的湿化学法有望用于制备高性能的WO3基电致变色器件.
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