Development of Novel PEDOT:PSS Fabrication Techniques for High Performance, Flexible RFID Antennas and Energy Storage Devices

Abstract

Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been widely studied as either nanometre-scale, transparent films or a conductive, capacitive composite material in electronic devices. While significant effort has been directed towards increasing PEDOT:PSS conductivity in transparent films, very little nanoscale, morphological consideration has been applied to micron-scale PEDOT:PSS materials. As a result, PEDOT:PSS conductivity often decreases in micron-scale materials, and the polymer has been largely overlooked as a high performance material in practical applications. In this thesis, PEDOT:PSS fabrication techniques are optimised to produce high conductivity and high electrochemical performance micron-scale quantities of PEDOT:PSS. The optimised PEDOT:PSS is used to fabricate an RFID antenna with extraordinary radiation efficiency, a high efficiency zinc/bromine flow battery anode, and an ultra-high performance composite-fibre-supercapacitor. A novel fabrication technique was developed to maintain PEDOT:PSS electrical and electrochemical performance in micron-scale applications. By submersion in ethylene glycol, PEDOT:PSS phase separation, conformational changes, stability and PEDOT loading were optimised for a commercially available PEDOT:PSS. Polymer films 40 m thick were reliably produced with over 500 S cm-1. The high performance PEDOT:PSS was fabricated into a 2.45 GHz RFID dipole antenna, achieving 99.7% peak radiation efficiency, a novel result for a non-metal antenna. The same morphologically considerate approach was applied to zinc/bromine flow battery anode design, more than doubling peak charge density. Energy density increased by over 50%, and charge efficiency increased by 9.3%, directly increasing battery efficiency. PEDOT:PSS was composited with reduced graphene oxide to produce a symmetric fibre supercapacitor with very high capacitance, 138 F cm-3 compared to 55 F cm-3 and 14 F cm-3 for PEDOT:PSS and rGO respectively.