Post treated PEDOT-PSS films with excellent conductivity and optical properties as multifunctional flexible electrodes for possible optoelectronic and energy storage applications

Abstract

Organic electronic devices with low cost, wearable and flexible electrodes have become forefront of scientific and technological development of optoelectronic research. Electrode fabrication techniques with superior multi-functionalities such as conductivity, optical transparency, and mechanical flexibility remains a biggest challenge for research community. Herein, we present a strategy to develop highly conductive, transparent and flexible electrodes based on post-treated Poly (3,4-ethylenedioxythiophene): Poly (styrene sulfonate) (PEDOT: PSS) films on a Polyethylene terephthalate (PET) substrate for possible optoelectronic and energy storage applications. Commercially available PEDOT-PSS doped with secondary solvent such as N,N-Dimethylformamide (DMF) was spin coated onto PET substrate followed by camphor sulphonic acid (CSA) post-treatment. Doping of DMF followed by CSA post-treatment significantly enhances the conductivity of PEDOT-PSS films from 1.5 S cm−1 to 1826 S cm−1. Optical transmittance of 87% was achieved in the post-treated PEDOT-PSS films in comparison to 92% for PET substrate. The influence of rotation speed, rotation time of coating unit, and number of fabricated layers on opto-electronic properties of post-treated PEDOT-PSS films were investigated in detail. Improved electrical conductivity, optical conductivity, dielectric constant, and refractive index associated with photon energies suggests significant removal of insulating PSS segments and formation of localized energy states within energy band gap of post-treated films. The post-treated flexible PEDOT-PSS films exhibit excellent stability interms of conductivity and optical transmittance for a period of 30 days under ambient conditions. Furthermore, the post-treated PEDOT-PSS films show improved electrochemical performance to be used as flexible electrode in supercapacitors. This study demonstrates an efficient strategy to fabricate highly conductive, flexible electrodes based on PEDOT-PSS films with superior optical and electrochemical properties for a possible optoelectronic and energy storage applications.