All-in-one electrochromic devices (ECDs) have potential applications in wearable stretchable electronics. However, ECDs today are inflexible, slow to respond and at risk of electrolyte leakage. We have prepared a novel electrochromic hydrogel by introducing polyoxometalates [PWO] (PW) into polyacrylamide (PAAm) via ionic and covalent cross-linking. Negatively charged PW have ionic conductive properties, thus the hydrogel is able to undergo electrochromic behavior without the addition of electrolytes. PAAm/PW hydrogel has good flexibility and tensile properties, high transparency and a simple preparation process. The PAAm/PW hydrogel is reversibly switchable between colorless and dark blue over a voltage range from 0 V to −2.8 V. The ECDs had a large transmittance contrast (53.7 %), fast response time (coloring/bleaching times of 6.9 s and 5.6 s) and satisfactory coloring efficiency (125.5 cm/C). PAAm/PW hydrogel has good open-circuit memory properties which maintains coloring state after 7 days of power off. The sandwich-structured (ITO/hydrogel/ITO) electrochromic device based on this hydrogel is simple to manufacture, low in cost and fast in response, which have potential applications in the fields of smart windows, energy-saving displays, and anti-glare mirrors.

中文翻译：

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基于 PAAm/P2W18 水凝胶的一体化快速响应电致变色器件，无需额外电解质


一体化电致变色器件（ECD）在可穿戴可拉伸电子产品中具有潜在的应用前景。然而，如今的 ECD 不灵活、响应缓慢且存在电解液泄漏的风险。我们通过离子和共价交联将多金属氧酸盐[PWO]（PW）引入聚丙烯酰胺（PAAm）中，制备了一种新型电致变色水凝胶。带负电的PW具有离子导电特性，因此水凝胶能够在不添加电解质的情况下发生电致变色行为。 PAAm/PW水凝胶具有良好的柔韧性和拉伸性能、透明度高、制备工艺简单。 PAAm/PW 水凝胶在 0 V 至 -2.8 V 的电压范围内可在无色和深蓝色之间可逆地切换。ECD 具有较大的透射比对比度 (53.7%)、快速的响应时间（着色/漂白时间分别为 6.9 秒和 5.6 秒） s) 和令人满意的着色效率 (125.5 cm/C)。 PAAm/PW水凝胶具有良好的开路记忆性能，断电7天仍能保持着色状态。基于该水凝胶的三明治结构（ITO/水凝胶/ITO）电致变色器件制造简单、成本低廉、响应速度快，在智能窗、节能显示、防眩光等领域具有潜在的应用前景镜子。