乙醇胺强化解离WO_(3)·H_(2)O微米片制备柔性WOx电致变色器件

Monoethanolamine-Intensified Dissociation of WO_(3)·H_(2)O Microplates to Fabricate Flexible WOx Electrochromic Devices

WO_(3)电致变色器件具有变色响应时间短、光学对比度高等优点,在汽车后视镜、智能窗等领域具有重要应用。近年来,随着可穿戴电子设备的迅速发展,柔性WO_(3)薄膜的制备成为柔性电致变色器件领域的研究热点。但WO_(3)结晶温度较高,而受聚合物衬底可耐受温度的限制,通常需要采用磁控溅射、电子束蒸镀等真空气相沉积技术制备晶态柔性WO_(3)薄膜。此技术对设备要求高,且所制备的薄膜结构较致密,不利于电解液的渗透和电解质离子的快速脱嵌。采用液相回流化学法预合成了结晶态WO_(3)·H_(2)O微米片粉体,首次采用乙醇胺等胺类分子使WO_(3)·H_(2)O强化解离为高度分散的纳米粒子胶体溶液,经旋转涂覆液相成膜技术制备成柔性晶态WO_(x)薄膜并应用于柔性电致变色器件。机理研究表明,胺基官能团与WO_(3)·H_(2)O微米片的强界面相互作用产生的电荷斥力使其迅速解离。所制备的柔性WO_(x)电致变色器件的着色和褪色时间分别为5.9 s和5.4 s,着色效率最高可达146.7 cm^(2)/C,经200次弯折后仍具有较好的性能。

WO_(3) electrochromic devices(ECDs)with the short response time and high optical contrast show great application potentials in car rearview mirrors and smart windows.With the rapid development of wearable electronics,the fabrication of flexible WO_(3) films for bendable ECDs has attracted much attention.However,the fabrication of flexible crystalline WO_(3) films generally requires a sophisticated vacuum vapor deposition technique,including magnetron sputtering and electron-beam deposition due to the high crystallization temperature of WO_(3) and the limited endurable temperature of polymer substrates.The dense WO_(3) layers on polymer substrates affect the facile access of electrolyte and fast intercalation/deintercalation of electrolyte ions.In this paper,well-crystallized WO_(3)·H_(2)O microplate powders were pre-synthesized by a chemical reflux method.Monoethanolamine was utilized to intensively dissociate WO_(3)·H_(2)O microplates into a well-dispersed colloidal solution.The flexible nanocrystalline WO_(x)/polyethylene terephthalate films were fabricated via spin coating deposition and assembled into the flexible ECDs.The accumulated charge repulsion provided by the intense interfacial interaction between amine group and WO_(3)·H_(2)O microplates results in their fast dissociation.The fabricated flexible crystalline WO_(x) electrochromic devices have short coloring and bleaching time of 5.9 s and 5.4 s,respectively,and a coloring efficiency of 146.7 cm^(2)/C,and still exhibit the superior performance after 200 bending cycles.