奈米工程與微系統研究所專題演講

Keynote Speech of of Inst. NanoEngineering and MicroSystems

時間：2014年10月17日 2-4PM     地點：工程一館108室

1400-1600 on Oct. 17, 2014 in Room 108 of Engineering Building I

演講者(Speaker)：阮修林副教授 （Prof. Xiulin Ruan）

任職單位(Affiliation)：普渡大學(Mechanical Engineering at Purdue University)

講題(Topic): Engineering Thermal Transport at the Nanoscale

Thermal transport is a key issue that limits many important energy transfer and conversion applications such as solar thermal and photovoltaics, thermoelectrics, and thermal management of electronic devices. In this talk I will give examples of how thermal conductive and radiative transport can be engineered using boundary, interface, confinement, and nonlinear effects in nanostructures, in order to significantly improve the performance of these applications.  We use the “nanomaterials by design” approach, i.e., predicting thermal conductive and radiative properties of solids from their atomic structures and then validating the predictions with experiments. The predictions are done through multiscale multiphysics simulation methods that bridge first-principles calculations, molecular dynamics, Boltzmann transport equation, and finite difference/element methods. The first part of the talk will cover solar thermal and photovoltaic applications using carbon nanotube, silicon nanowire, and graphene arrays. We predict the dielectric function using first-principles methods together with Fermi’s Golden Rule. The results are then implemented into finite difference time domain (FDTD) calculations to demonstrate the extremely high optical absorption. The findings are validated by our synthesis of these nanostructure arrays and characterizations of their high optical absorption. The second part will cover systematic multiscale simulations of thermal transport in a variety of graphene structures which are of significance for the next generation electronics, including suspended and supported graphene, as well as graphene nanoribbons. In particular, asymmetric graphene nanoribbons show interesting thermal diode behavior that can potentially be used to make devices that can control heat flow.  The third part of the talk covers thermal transport in thermoelectric materials.  We use ab initio calculations to develop empirical interatomic potentials for heavy metal compounds including Bi2Te3 and PbTe, and then use molecular dynamics to predict thermal conductivities of bulk, nanowires, and few-quintuple thin films. Using phonon spectral analysis, the mode-resolved phonon mean-free-path is derived which provide very useful insights of thermal conductivity size effects. Several thermoelectric nanostructures have been developed successfully under theoretical guidance.

Short bio: Dr. Xiulin Ruan is an associate professor in the School of Mechanical Engineering at Purdue University.  He received his B.S. (in 2000) and M.S. (in 2002) from the Department of Engineering Mechanics at Tsinghua University (Beijing). He then received another M.S. in electrical engineering (in 2006) and Ph.D. in mechanical engineering (in 2007) from the University of Michigan at Ann Arbor, before joining Purdue.  He is a recipient of the NSF CAREER Award, the Air Force Summer Faculty Fellowship, the Purdue University Bravo Award, and Purdue Seed for Success Award, among his honors. He has been an Editorial Board member for the journal Scientific Reports since 2012. His research and teaching interests are focused on multiscale multiphysics simulations and experiments of thermal transport and conversion that involve photons, phonons, and electrons. He has published 53 journal papers on these topics.

主辦：清華大學奈米工程與微系統研究所

協辦：清華大學工學院、動力機械工程學系

連絡人：饒達仁 E-mail：djyao@mx.nthu.edu.tw