Super High Conductivity PEDOT: PSS via Methanol-Benzoic Acid Co-Modification for Flexible Supercapacitors With Excellent Capacitance.

The advancement of flexible electronics demands conductive polymers that combine high conductivity, optical transparency, and mechanical resilience. Poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) has emerged as a promising candidate for capacitive touchscreens and flexible energy storage devices, yet its widespread adoption has been hindered by the intrinsic trade-off between conductivity enhancement and material compatibility. While strong acids can significantly improve PEDOT:PSS conductivity, their corrosive nature causes irreversible damage to device components. Here, we develop a benign methanol-benzoic acid co-modification strategy that achieves unprecedented performance metrics. The optimized PEDOT:PSS films demonstrate a record conductivity of 3760 S/cm among organic-modified systems while maintaining optical transparency and mechanical flexibility. Comprehensive spectroscopic characterization reveals that the conductivity enhancement originates from partial PSS removal and structural reorganization into quinoid-dominated configurations. When implemented in flexible supercapacitors, these modified electrodes deliver exceptional electrochemical performance, including an areal capacitance of 852 mF/cm2 85.2 F/cm3 volumetric) at 0.5 mA/cm2 with outstanding rate capability (71% retention at 10 mA/cm2) and cycling stability (90% capacity retention after 10 000 cycles). The devices achieve remarkable energy densities of 32.8 µWh/cm2 (areal) and 7.14 mWh/cm3 (volumetric), surpassing most reported PEDOT-based supercapacitors. This work establishes a material-friendly approach to engineer high-performance conductive polymers for next-generation flexible electronics.