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

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.