报告人：Prof. Sang-Woo-Kim（Sungkyunkwan University）
报告题目：Triboelectric and Piezoelectric Properties of Nanomaterials for Self-Powered Electronics
Energy harvesting systems based on piezoelectric and triboelectric nanomaterials are in great demand, as they can provide routes for the development of self-powered devices which are highly flexible, stretchable, mechanically durable, and can be used in a wide range of applications. Our recent research interest mainly focuses on the fabrication of piezoelectric and triboelectric power generators based on various kinds of nanomaterials. Flexible generators exhibit good performances and are easy to integrate which make it the perfect candidate for many applications, and therefore crucial to develop. In this presentation, I firstly introduce the fundamentals and possible device applications of piezoelectric and triboelectric nanogenerators, including their basic operation modes. Then the different improvement parameters will be discussed. As main topics, I will present a couple of recent achievements regarding highly stretchable piezoelectric-pyroelectric hybrid generators, transparent flexible triboelectric nanogenerators, textile-based wearable triboelectric nanogenerators, highly robust nanogenerators with a shape memory function etc. The recent research and design efforts for enhancing power generation performance of nanogenerators to realize self powering of portable and wearable sensors and electronics will also be discussed in this talk. In addtion, I will address a high performance inertia driven triboelectric nanogenerator based on body motion and gravity. The packaged device has successfully harvested around 144 mW during day time in preclinical test, and real-time output voltage data is monitored via Bluetooth low energy information transmit system.
As the second topic, I am going to introduce a graphene tribotronic touch sensor which is based on coplanar coupling of a single electrode mode triboelectric nanogenerator (S-TENG) and a graphene FET. When any object (e.g. human finger) comes into contact with friction layer of the S-TENG, the charges are produced due to well-known triboelectric effect. The triboelectric charges act as a gate bias to the graphene FET and modulates its current transport. The tribotronic sensors have displayed a sensitivity of ~2% kPa-1, a limit of detection <1 kPa, and a response time of ~30 ms. Furthermore, the devices can effectively detect touch stimuli from both bare and gloved fingers which can be a limitation with capacitive touch screens. Finally I will introduce tunneling-triboelectrification for defining on demand rewritable ghost floating gates below graphene with the extraordinary spatial resolution of AFM. Tunneling-triboelectrification is the friction-induced tunneling of charges through graphene and their accurate localization on the insulator underneath the graphene. The charges injected by tunneling-triboelectrification exhibit impressively long lifetimes. After tunneling-triboelectrification, the charges very effectively controlled the properties of the graphene, thus behaving as immaterial, charges-only, ghost floating gates which can be repeatedly created, modified or destroyed.
Dr. Sang-Woo Kimis a full professor and SKKU Fellow in the Department of Advanced Materials Science and Engineering at Sungkyunkwan University (SKKU). He received a Ph.D. in Electronic Science and Engineering from Kyoto University in 2004. After working as a postdoctoral researcher at Kyoto University and University of Cambridge, he spent 4 years as an assistant professor at Kumoh National Institute of Technology. He joined SKKU in 2009.He recently receivedMCARE 2016 Award (ACerS-KIChE), The Republic of Korea President’s Award for Scientific Excellence (2015), National Top 100 Research Award (2015), etc. His recent research interest is focused on piezoelectric/triboelectric nanogenerators, photovoltaics, and 2D materials including graphene, h-BN, and TMDs. He has published over 200 research papers (h-index of 54) and holds over 100 domestic/international patents. Now he is a director of SAMSUNG-SKKU Graphene/2D Research Center and is leading National Research Laboratory for Next Generation Hybrid Energy Harvester. He is currently serving as an Associate Editor of Nano Energy (Elsevier) and an Executive Board Member of Advanced Electronic Materials (Wiley).