Light-Induced Enhancement of Cross-Linked Viologen-Fluorene Polymer Electrode for High-Performance Supercapacitors.

Porous organic polymers (POPs) are generally prepared as insoluble powders and coated onto the electrode surface with another polymer binders such as PVDF: HFP during electrode preparation. POP-based electrodes formed through surface cross-linking hold promise for supercapacitor applications. In this study, a new pyridinium-fluorene donor-acceptor monomer (FBP_allyl) was synthesized and cross-linked onto graphene sheet conductive substrates via a thiol-ene click reaction to prepare a photoactive polymer electrode with light-harvesting and charge storage capability. The specific capacitance of the fabricated electrodes at 2.0 A/g was almost doubled under visible light, from 152.7 F/g (dark) to 304.1 F/g (light). In a three-electrode configuration, the electrochemical cell exhibited a power density of over 3000 W/kg, while the energy density increased from 35 to 60 Wh/kg under illumination. Furthermore, the prepared electrode cell showed long-term stability over 10,000 cycles, demonstrating that combining donor-acceptor engineering with thiol-ene cross-coupling is an effective approach for developing photoassisted capacitors with improved electrochemical performance.