Seminar Speaker: John Reynolds, Georgia Tech

From Spin to Spray to Blade: Processing Pi Conjugated Polymers for Solid State and Redox-Active Applications

Abstract

As the design of the repeat unit structures of conjugated polymers has become more mature for targeting both solid-state and redox-active properties, methods of processing have become more important for controlling properties. While spin-coating remains a laboratory go-to method, processing via roll-to-roll compatible production approaches has become more prevalent. We start by detailing how electron-rich redox switchable electrochromic polymer (ECP) films attained via spray processing yield fast switching, vibrant color to transmissive, EC films. These ECP inks allow solution blending for color control, in essence attaining a full-color palette. Blade coating of nanoparticles of indium tin oxide (nano-ITO) is used to provide capacitive counter electrodes that effectively serve as charge-storing films in high optical density and high contrast electrochromic devices with the ECPs. By functionalizing 3,4-ethylenedioxythiophene (EDOT) with flexible ester-containing side chains, soluble redox active polymer films are formed via blade coating. Chemically cleaving these side chains by hydrolysis, the electroactive fraction of the conjugated polymer is increased as the film compacts and loses thickness. By maximizing the EDOT content in these polymers, we can minimize the amount of chemically saturated components, densify the films upon side chain cleavage, and provide materials with electrical conductivities over 1,000 S/cm when oxidatively doped.

Biography

Dr. John R. Reynolds is a Professor of Chemistry Biochemistry, and Materials Science and Engineering at the Georgia Institute of Technology with expertise in polymer chemistry. He serves as a member of the Center for Organic Photonics and Electronics (COPE) and is the founding Director of the Georgia Tech Polymer Network (GTPN). His research interests have involved electrically conducting and electroactive conjugated polymers for ~40 years with work focused on the development of new polymers by manipulating their fundamental organic structure to control their optoelectronic and redox properties. His group has been heavily involved in developing new poly heterocycles for visible and infrared light electrochromism, along with light emission from polymer and composite LEDs (both visible and near-infrared) and light-emitting electrochemical cells (LECs). Further work is directed to using organic polymers and oligomers in charge of storing supercapacitors, photovoltaic cells and bio-electronic devices. Reynolds obtained his M.S. (1982) and Ph.D. (1984) degrees from the University of Massachusetts in Polymer Science and Engineering, he has published over 475 peer-reviewed scientific papers, has ~45 patents issued and ~10 patents pending, and serves as co-editor of the “Handbook of Conducting Polymers”. He was awarded the ACS Cope Scholar Award in 2020, the ACS Florida Award in 2019, the ACS Applied Polymer Science Award in 2012 and is a Fellow of the Royal Society of Chemistry and the Materials Research Society. He has served on the editorial board for the journals ACS Central Science, Macromolecules, Chemistry of Materials, ACS Applied Materials and Interfaces, Macromolecular Rapid Communications, Polymers for Advanced Technologies, and the Journal of Macromolecular Science, Chemistry.