SCC/PVA Hydrogel with Self‐Healing Capability for Electrochromic Device

Abstract Cracking caused by aging or repeated bending can severely affect the lifetime of electrochromic devices. In this work, a self‐healing electrochromic hydrogel was developed with poly (vinyl alcohol) (PVA)‐sodium carboxymethyl chitosan (SCC) semi‐inter transfer network as the matrix, viologen bromide (HPV 2+ 2Br − ) as the electrochromic substance, and borax as the cross‐linking agent. The self‐healing properties of hydrogel stem from the dynamic and reversible borate bonds between borax and PVA molecular chains. As the voltage changes, the color of the device transitions from colorless to light purple and then to dark purple. The optical contrast at 600 nm reaches approximately 51 %. At room temperature, the disconnected hydrogel can fully restore its original state after 30 minutes of contact, effectively addressing issues related to cracks and damage in flexible electrochromic devices. This research holds significant implications for enhancing the reliability and stability of flexible electrochromic devices.