Research Team at Korea University of Technology and Education
Domestic researchers have developed a device that can stretch freely like fabric and become transparent, making it applicable to electronic skin (e-skin) and smart clothes.
The National Research Foundation of Korea announced on the 6th that Professor Jinwoo Bae's research team at Korea University of Technology and Education developed an "integrated electrochromic ion gel-based highly flexible and highly stretchable electrochromic device" that can control color and transmittance at low voltage using a water-resistant, highly transparent, and highly stretchable polyvinyl chloride (PVC) polymer-based electrochromic ion gel and transparent electrodes. Electrochromic technology changes the color of a material through electrochemical reactions, with smart windows being a representative example.
Recently, interest in stretchable transparent displays and wearable devices has increased, leading to active research on related electronic devices. Among them, electrochromic devices that change color when an external voltage is applied have attracted much attention due to their low driving voltage and simple device configuration. However, existing inorganic-based electrochromic devices lack stretchability, limiting their applications. To address this, electrochromic devices using hydrogel-based electrolytes containing water have been developed, but they faced issues such as electrolyte leakage or evaporation depending on temperature and humidity conditions, which degraded electrochromic performance.
The research team succeeded in developing a highly stretchable electrochromic device that overcomes the above shortcomings of existing electrochromic devices. By adding plasticizers to the PVC polymer and adjusting the content of ionic liquids and the electrochromic material viologen, they developed an integrated electrochromic ion gel with water resistance, high transparency, and high stretchability. The optimized electrochromic ion gel maintained its shape and form over a long time without being sensitive to changes in ambient temperature and humidity, and exhibited high transparency, high stretchability, and high ionic conductivity.
The research team implemented flexible and stretchable electrochromic devices using the developed electrochromic ion gel and transparent electrodes. The flexible electrochromic device demonstrated excellent color-changing performance and outstanding bending durability, while the stretchable electrochromic device successfully maintained stable color change even after twisting or multiple folds.
Professor Bae explained, “We realized a high-performance stretchable electrochromic device through a simple structure and straightforward fabrication process,” adding, “It is expected to be applicable in various fields such as next-generation wearable devices like electronic skin (e-skin), smart clothes, smart camouflage, and stretchable transparent displays.”
The research results were published online on May 6 in the international journal in the field of chemical engineering, Chemical Engineering Journal.
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