Multichromatic Realization of Electrochromic Supercapacitors by Using TT-OMe/EDOT Copolymer Bifunctional Electrodes

Abstract

Electrochromic supercapacitors (ECSs), which combine energy storage with real-time optical indication of charge states, have emerged as promising candidates for next-generation intelligent energy storage technologies amid mounting energy and environmental challenges. Among them, conventional conductive homopolymer such as 3,4-ethylenedioxythiophene (EDOT) for ECS suffers from limited electrochemical performance due to unstable microstructures. In this work, a series of poly(3,6-dimethoxythieno[3,2-b]thiophene-co-3,4-ethylenedioxythiophene) (P(TT-OMe-co-EDOT)) bifunctional electrodes were successfully fabricated via a one-step electrochemical copolymerization method. Tuning the TT-OMe/EDOT molar ratio enabled morphological optimization of the copolymer, in which EDOT incorporation induced a porous architecture that facilitated ion transport and enhanced electrochemical activity. As a result, the P(TT-OMe-co-EDOT) electrode delivered a high specific capacitance (218 F g^–1 at 5 mV s^–1) and enhanced stability (30.14% retention after 3000 cycles), along with tunable multicolor electrochromism. This study presents a facile in situ strategy for the fabrication of bifunctional electrode films, yielding materials that simultaneously exhibit enhanced electrochemical and electrochromic performance. These synergistic properties highlight their potential for integration into next-generation multifunctional energy storage systems.