π-Conjugation engineering in coordination metallopolymers for advanced electrochromic energy storage windows

Coordination metallopolymers (CMPs) have emerged as promising candidates for integrated electrochromic energy storage applications, leveraging their tunable structures that allow for precise control over their optical, electronic, and mechanical properties. However, achieving synergistic enhancement in both electrochromic and energy storage performance remains a significant challenge. To address this, we designed and synthesized two novel D-π-D structured CMPs featuring multiple redox-active centers by virtue of a π-conjugation engineering strategy via facile liquid-liquid interfacial polymerization. The resultant device achieved a high optical contrast of 54.1% at 750 nm, an improved area specific capacitance of 30.46 mF·cm^-2, and a rapid switching speed (2.3 s/1.2 s), attributed to efficient intramolecular charge delocalization and rapid charge transfer kinetics, stemming from the D-π-D molecular architecture. The fabricated smart window demonstrates an effective thermal insulation performance of 14.4 °C temperature reduction versus a general glass window. Furthermore, the electric energy involved in electrochromism could be recycled to power an LED for 30 s. This work provides a viable design strategy for developing high-performance CMPs with integrated electrochromic and energy storage functions.