Professor, Osaka University, Japan
Title: Nanostructure design and fabrication for high performance thermoelectric material
Abstract: High performance thermoelectric materials have been intensively studied because thermoelectric conversion has been expected to generate an ideal energy source. The thermoelectric conversion efficiency is monotonically increasing with dimensionless figure of merit ZT. However, large ZT is difficult to be obtained because ZT-determining factors (Seebeck coefficient, electrical conductivity, and thermal conductivity) have trade-off relationship. Nanostructuring is an approach to enhance ZT. In terms of scientific and application views, it is important to elucidate what nanostructures are best for ZT enhancement and its mechanism. Well-controlled nanostructure fabrication technique is required to do so. For ten years, we have been seeking some of the best nanostructures for ZT enhancement using the atomically-controlled nanostructure fabrication technique [1-5]. We fabricated well-controlled nanostructures as Si-based films to reduce thermal conductivity using coherent phonon transport. Furthermore, we evolved fabrication techniques from nanostructure to atomic structure to enhance power factor We developed layered silicene structures with atomic position controlled resulting in high power factor which is corresponding to 3000 times enhancement compared with the preceding result. In the talk, I will introduce the well-controlled nanostructure fabrication technique, the resulting thermoelectric enhancement, and discuss their physics.
Prof. Yoshiaki Nakamura received his B. Eng. and M. Eng. from the University of Tokyo, Japan in 1997 and 1999, respectively, and obtained Ph. D. from Department of Applied Physics, Graduate School of Engineering, the University of Tokyo, Japan, 2002. He was also a PRESTO researcher, Japan Science and Technology Agency (2010-2014). His research covers fabrication and physical properties of nanostructures, surface science, molecular beam epitaxy. He is currently a professor at Osaka University, and works on development of Si-based thermoelectric nanomaterials.
Host: Dr. Mona Zebarjadi
Organizer: Dr. Mona Zebarjadi