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

ABSTRACT 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/cm 2 85.2 F/cm 3 volumetric) at 0.5 mA/cm 2 with outstanding rate capability (71% retention at 10 mA/cm 2 ) and cycling stability (90% capacity retention after 10 000 cycles). The devices achieve remarkable energy densities of 32.8 µWh/cm 2 (areal) and 7.14 mWh/cm 3 (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.