Engineering redox-active benzo[1,2-b:4,5-b′]dithiophene-based conjugated polymers: tuning porosity and linker architecture for high-performance supercapacitors†

Abstract

Conjugated polymers have emerged as promising candidates for next-generation supercapacitor electrodes due to their high conductivity, redox activity, and π-conjugated frameworks. In this work, we conduct a comprehensive investigation into how porosity and linker architecture affect the electrochemical properties of four conjugated polymers that incorporate the redox-active benzo[1,2-b:4,5-b′]dithiophene-4,8-dione (DTDO) units. Specifically, two types of porous polymers (Ph-DTDO porous and TEPh-DTDO porous) and two types of linear polymers (Ph-DTDO linear and DEPh-DTDO linear) are synthesized using Suzuki and Sonogashira coupling reactions, employing structurally tailored phenyl-based linkers. Among them, the Ph-DTDO porous conjugated polymer demonstrates superior performance, delivering a high specific capacitance of 842.4 F g⁻¹ at 0.5 A g⁻¹ and excellent stability with 98.78% retention after 6000 cycles in a three-electrode system. Furthermore, the symmetric supercapacitor device assembled with the Ph-DTDO porous polymer exhibits an energy density of 59.4 W h kg⁻¹ and a specific capacitance of 428.21 F g⁻¹. Comparative analysis reveals that the porous architecture and phenyl-bridged linker facilitate enhanced ion diffusion, higher capacitive contribution, lower charge transfer resistance, and improved π–π stacking interactions, thus significantly boosting the energy storage capabilities. This work underscores the crucial role of structural engineering in conjugated polymers and offers valuable design insights for high-performance energy storage materials.