Jeon Ie-Rang, Kang Joo-Hee, Paek Seung-Min, Hwang Seong-Ju, Choy Jin-Ho
Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nanoscience, Ewha Womans University, Seoul 120-750, Korea.
J Nanosci Nanotechnol. 2011 Jul;11(7):6518-22. doi: 10.1166/jnn.2011.4354.
Electrochromic tungsten oxide (WO3) films on ITO glass were fabricated by spin-coating with a tungsten peroxy acid solution, which was prepared by adding an equivolume mixture of hydrogen peroxide and glacial acetic acid to tungsten metal powder. The structural evolution of the tungstate precursor upon heat treatment was studied by X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) analyses, which indicated that the as-synthesized tungstate transformed into nanocrystalline WO3 upon heating. It is, therefore, quite clear that as-synthesized tungstate can be a good precursor for electrochromic WO3 films. A series of WO3 thin films were prepared on ITO glass by spin-coating with different concentrations of tungsten peroxy acid solution and then post-annealing at various temperatures. Depending on the concentration of the tungstate coating solution (200-500 mg mL(-1)) and the annealing temperature (100-300 degrees C), the thickness and WO3 content as well as the electrochromic properties of WO3 films can be controlled. As a result, the optimum fabrication conditions were determined to be a tungstate solution concentration of 300-400 mg mL(-1) and a post-annealing temperature of 200 degrees C. Finally, an inorganic-inorganic hybrid electrochromic device (ECD) composed of optimized WO3 and Prussian Blue (PB) with desirable coloration efficiency was successfully developed.
通过旋涂钨过氧酸溶液在ITO玻璃上制备了电致变色氧化钨（WO₃）薄膜，该溶液是通过向钨金属粉末中加入等体积的过氧化氢和冰醋酸的混合物制备而成。通过X射线衍射（XRD）和X射线吸收近边结构（XANES）分析研究了热处理过程中钨酸盐前驱体的结构演变，结果表明，合成的钨酸盐在加热时转变为纳米晶WO₃。因此，很明显，合成的钨酸盐可以作为电致变色WO₃薄膜的良好前驱体。通过旋涂不同浓度的钨过氧酸溶液，然后在不同温度下进行后退火处理，在ITO玻璃上制备了一系列WO₃薄膜。根据钨酸盐涂层溶液的浓度（200 - 500 mg mL⁻¹）和退火温度（100 - 300℃），可以控制WO₃薄膜的厚度、WO₃含量以及电致变色性能。结果确定最佳制备条件为钨酸盐溶液浓度为300 - 400 mg mL⁻¹，后退火温度为200℃。最后，成功开发了一种由优化的WO₃和普鲁士蓝（PB）组成的具有理想着色效率的无机-无机混合电致变色器件（ECD）。
