Probing Kinetics of Charge Transport in Organic Mixed Ionic Electronic Conductors: From Neuromorphic Transistors to Energy Storage
Guest Speaker：Professor David S. Ginger, University of Washington
Inviter: Professor Tao Deng
Date&Time: Friday 23. Feb. 10:00-11:30
Venue: Yiucheng Lecture Hall (500), Xu Zuyao Building
Biography:
David S. Ginger earned dual B.S. degrees in chemistry and physics at Indiana University with departmental honors and highest distinction, performing undergraduate research with Victor E. Viola. He received a British Marshall Scholarship and an NSF Graduate Fellowship and completed his Ph.D. in physics with Neil C. Greenham in the Optoelectronics group at the University of Cambridge (UK).
After a joint NIH and DuPont Postdoctoral Fellowship at Northwestern University in Chad Mirkin’s lab, he joined the faculty at the University of Washington in Seattle where he is currently the B. Seymour Rabinovitch Endowed Chair in Chemistry, Washington Research Foundation Distinguished Scholar in Clean Energy, and Adjunct Professor of Physics. He serves as the Chief Scientist of the Washington state funded UW Clean Energy Institute.
He holds a joint appointment as a Lab Fellow at Pacific Northwest National Lab (PNNL), and is the founding director of the NSF Science and Technology Center for the Integration of Modern Optoelectronic Materials on Demand (IMOD).
He is a Fellow of the Materials Research Society, a member of the Washington State Academy of Sciences, a Fellow of the AAAS (American Association for the Advancement of Science) and has been named a Research Corporation Cottrell Scholar, a Research Corporation Scialog Fellow in solar energy conversion, an Alfred P. Sloan Foundation Research Fellow, and a Camille Dreyfus Teacher-Scholar. He has received the Presidential Early Career Award for Scientists and Engineers, and the ACS Unilever Award in Colloid and Surfactant Science. He is the 2012 recipient of the Burton Medal of the Microscopy Society of America, and was honored as a Finalist for the Blavatnik National Awards for Young Scientists in 2016. He is also an Associate Editor of the ACS journal Chemical Reviews.
His research centers on the physical chemistry of nanostructured materials with applications in optoelectronics, energy and sensing, and his group makes use of techniques ranging from scanning probe microscopy to optical spectroscopy.
Abstract:
Ion injection and transport in organic semiconductors affects the performance of devices ranging from organic electrochemical transistors (OECT) for bioelectronic signal transduction, to next generation neuromorphic circuit elements, to aqueous polymer batteries. The performance of conjugated polymers in these applications is due to the ability of the semiconductor to accommodate ionic countercharge throughout the device volume during redox processes. Using OECTs as a testbed, we explore mixed transport kinetics on different polymers with different counterions. At the nanoscale, we use electrochemical strain microscopy (ESM) to probe local swelling resulting from ion uptake, and photoinduced force microscopy (PiFM) to probe the IR fingerprints of ion injection which we correlate with ensemble measurements such as electrochemical quartz crystal microbalance (eQCM), spectroelectrochemistry, and in operando synchrotron structure measurements. Focusing on asymmetric switching kinetics which defy description by conventional device models, we image the local doping level of OECT transistor channels and show that device turn-on occurs in two stages, while turn-off occurs in one stage. We attribute the faster turn-off to a combination of engineering as well as physical and chemical factors including channel geometry, differences in doping and de-doping kinetics and, critically, the physical phenomena of carrier density-dependent mobility.