Layer‐By‐Layer Approach to Improve the Capacitance of Conducting Polymer Films

Abstract In the pursuit of energy storage devices offering high power density, rapid charge and discharge rates, a layer‐by‐layer deposition approach is shown to improve the capacitive properties of conducting polymer‐based devices. This work describes the synthesis and characterization of a composite material based on poly(3,4‐ethylenedioxythiophene) (PEDOT) and poly(3,4‐ethylenedioxypyrrole) (PEDOP) for supercapacitor applications. PEDOT and PEDOP are sequentially electropolymerized using cyclic voltammetry to form bilayer structures, overcoming challenges associated with copolymerization. The evaluation of electrochemical performance of the PEDOT/PEDOP composite reveals superior areal capacitance (42.2 ± 2.8 mF cm−2 at the scan rate of 5 mV s−1) outperforming both homopolymers by up to 30%. Microscopic and spectroscopic surface analysis confirm the uniform coating of PEDOT/PEDOP and enhanced surface roughness resulting from the formation of 3D nanostructures, contributing to improved electrochemical performance. Further electrochemical impedance spectroscopic analysis demonstrates low charge transfer resistance (25 ± 8 Ω) and high energy density with respect to the area of the electrode (3.53 ± 0.3 µWh cm−2 at 55 µW cm−2), making PEDOT/PEDOP composite a promising material for high‐performance supercapacitors.