High-Performance Electrochromic Polymers Enabled by Side-Chain Engineering for Intelligent Windows and Supercapacitors

The advancement of high-performance electrochromic polymers with integrated energy storage capabilities is crucial to addressing the growing demand for intelligent windows and supercapacitors. However, conventional conducting polymers face inherent trade-offs between stability, conductivity, and optical contrast, posing significant challenges to their practical application. Here, two novel high-performance electrochromic polymers, PmroDOTBDTPh and ProDOTBDTPh, were reported through specific side-chain modifications of an electrondonating phenyl ring unit embedded within the polymer backbone. Incorporating an oligo (ethylene glycol) side chains into the electron-rich benzene unit of PmroDOTBDTPh significantly enhanced intramolecular charge transfer, ion diffusion, and surface hydrophilicity, leading to improved optical contrast (40 %), faster response time (1.61 s), and higher coloration efficiency (186.88 cm2 C-1) in electrochromic devices compared to ProDOTBDTPh. PmroDOTBDTPh-based electrochromic devices also exhibited superior cycling stability, maintaining 93 % of the initial optical contrast even after 11,451 cycles. Furthermore, PmroDOTBDTPh applied in supercapacitors demonstrated excellent charge storage capacity due to lower self-loss demonstrating its potential as a promising dual-functional material. This work provides new insights into the design of advanced electrochromic materials for next-generation electrochromic and energy storage devices.