Stretchable interconnected modular electrochromic devices enabled by self-healing, self-adhesive, and ion-conducting polymer electrolyte

Here, we propose a versatile terpolymer electrolyte material, UPy-PEGMA-VBMI, comprised of three monomers: ureidopyrimidinone methacrylate (UPyMA), poly(ethylene glycol) methacrylate (PEGMA), and vinyl benzylmethylimidazolium (VBMI). The UPy-PEGMA-VBMI, supported by a combination of soft ethylene glycol chains, an ion-conducting imidazole unit, and self-complementary quadruple hydrogen bonds of UPy, exhibits exceptional properties such as high stretchability, rapid self-repair, solution processability, self-adhesion, and ion conduction. The UPy-PEGMA-VBMI was then applied to make ion gel composite films, demonstrating a notable ionic conductivity of 3.84 x 10-3 S cm-1 while maintaining robust stretching and adhesive characteristics. The electrochromic devices (ECDs) fabricated by this ion gel demonstrate outstanding performance, with fast switching times, long-term kinetic stability, and extraordinarily high coloration efficiency of 443.83 cm2 C-1. The stretchable ECDs are fabricated by utilizing the stretchable nature of UPy-PEGMA-VBMI, exhibiting a transmittance contrast of 42.7 % at an extension of 53 % and operational stability during stretching cycles. Moreover, self-healing and self-adhesive features enable the fabrication of interconnected modular ECDs, implementing area-scalable devices. These modular ECDs, each powered independently, provide arbitrary positioning and shifting of individual device patches, overcoming the performance limitations of conventional large-area devices. The unprecedented material and resulting devices open new possibilities for electrochromic applications, particularly in stretchable ECDs, pattern-switching devices, and scalable flexible ECDs.