Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan.
Phys Chem Chem Phys. 2009 Nov 14;11(42):9751-8. doi: 10.1039/b912202h. Epub 2009 Aug 25.
Porous tungsten oxide films of nanocrystalline tungsten oxide embedded in an amorphous tungsten oxide matrix have been synthesized via poly(ethylene glycol) (PEG)-template sol-gel technique with peroxopolytungstic acid precursor. The effects of PEG addition on the microstructure and electrochromic performance of the tungsten oxide films are investigated. Charge transfer/transport properties in the tungsten oxide films are studied by electrochemical impedance spectroscopy (EIS) as well. Triclinic tungsten oxide film is formed in the absence of PEG. The PEG-template tungsten oxide film demonstrates an electrochromic performance superior to that of the crystalline tungsten oxide film, including larger transmittance modulation and coloration/bleaching efficiency as well as faster response times. EIS measurements indicate that faster charge-transfer rates at the tungsten oxide/electrolyte interface and larger Li(+) diffusion coefficients in tungsten oxide are achieved in the PEG-template film. We suggest that the PEG-template tungsten oxide film with a porous crystalline/amorphous nanostructure provides an effective means for charge transfer/transport to encourage its superior electrochromic performance.
多孔氧化钨薄膜由嵌入非晶态氧化钨基质中的纳米晶氧化钨组成，通过过氧多钨酸前体的聚乙二醇（PEG）-模板溶胶-凝胶技术合成。研究了 PEG 添加对氧化钨薄膜微观结构和电致变色性能的影响。通过电化学阻抗谱（EIS）研究了氧化钨薄膜中的电荷转移/传输特性。在没有 PEG 的情况下形成三斜晶氧化钨薄膜。PEG-模板氧化钨薄膜表现出优于结晶氧化钨薄膜的电致变色性能，包括更大的透过率调制、着色/褪色效率以及更快的响应时间。EIS 测量表明，在 PEG-模板薄膜中，在氧化钨/电解质界面处更快的电荷转移速率和更大的 Li(+)扩散系数得以实现。我们认为，具有多孔结晶/非晶态纳米结构的 PEG-模板氧化钨薄膜为电荷转移/传输提供了一种有效手段，从而促进其优异的电致变色性能。
