(Invited) Transparent Conductive Films of PEDOT:PSS-Amino Acid Composite

Abstract

Transparent conductive electrode is an important component of optoelectronic devices such as light emitting diodes, photodiodes, and photovoltaic cells as well touchscreen technology. Growing demand for these technologies, as well as need for functionalities such as cost-effectiveness and flexibility, has resulted in various research on developing organic polymer-based transparent electrodes as an alternative to indium tin oxide (ITO) which is the current industry standard. One of the organic conducting polymers most commonly studied for their potential to be used as ITO-free transparent electrodes is PEDOT:PSS due to its high transmittance as a thin film, solution processability, flexibility, environmental stability, and commercial availability. There have been various works carried out to improve the conductivity of the PEDOT:PSS-based thin films by introducing dopants to improve the charge transport. We present our results demonstrating that not only the conductivity but also the transmittance of PEDOT-PSS-based films can be significantly improved by the introduction of amino acids such as phenylalanine in the film. We have observed that this enhancement in conductivity and optical transmittance of PEDOT:PSS-phenylalanine composite film is retained even when the amount of amino acid in the composite films is larger than the amount of PEDOT:PSS. We will present our study on the charge transport mechanism on these films based on electrochemical impedance spectroscopy (EIS) measurements. We will also further present our studies based on Scanning Electron Microscopy (SEM) as well as Scanning Probe Microscopy techniques such as topography imaging and conducting probe atomic force microscopy (CP-AFM) to elucidate the relationship between film morphology and charge transport in these composite films. The use of bioderived materials such as amino acids to create transparent composite films could open up avenues for developing and integrating bio-based materials in future electronics, help improve the environmental footprint of the electronics, and potentially also allow for the development of materials with a higher degree of biocompatibility for their application in bioelectronics.