Merging PEDOT and polyaniline for cost-effective yet high performance flexible electrochromic-supercapacitor dual device

Electrochromic-supercapacitor devices (ESDs) employing conjugated polymers (CPs) display elegant advantages in versatility and flexibility, which are essential for the development of multifunctional and wearable electronic devices. However, achieving both cost-effectiveness and high performance remains a considerable challenge in the preparation of CPs-based ESDs. Herein, we introduce a novel design strategy utilizing a conjugated polymer dual network (CPDN), specifically integrating poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI). This strategy involves the synthesis of a dual-target crosslinked precursor, followed by polymerized into a CPDN via one-step, low-potential electrochemical polymerization. The obtained polymer exhibits excellent electrochromic and capacitive performances, characterized by fast switching time (about 1 s), a high coloring efficiency (CE) value (322 cm² C⁻¹), a robust optical contrast (41 % at 610 nm), and an impressive specific capacitance (357 F g⁻¹ at 1 A g⁻¹). The fabricated flexible and economical ESDs by this CPDN demonstrate a reversible color transition between yellow and purple during the doping (charging) and dedoping (discharging) processes, maintaining 86.4 % stability after 1000 cycles. This feature facilitates the intelligent monitoring of energy storage levels in ESDs by visual color changes. The proposed polymer composite is therefore expected to provide an innovative CPs-based candidate for flexible ESDs.