【线上会议】声子曳引效应促进低温热电能源转换效率：第一性原理计算与优化（周嘉炜）

北岛

<会议简介>

计算材料线上研讨会（Computational Materials Online Seminar, CMOS）是一个以交流为目的非营利性的国际学术会议，以“开拓计算研究，促进材料发展”为宗旨，致力于服务从事计算材料研究的国内外相关人员，科学家和工程师。其涵盖的范围不仅包括材料学科，还包括物理、化学、生物、数学和工程等交叉领域。

CMOS采用国际学术会议标准，依托于互联网，基于专题组织者负责的小组在线讨论形式，突破传统会议的时间、地域限制，旨在为材料科学等领域的学术交流提供灵活的协作、讨论、交流环境，增进国内外学术同行的交流。该研讨会的使命是促进学术沟通，拓展科学研究。

了解第1704期更多内容：【会议预告】2017计算材料线上研讨会（第1704期）持续来袭！8月每周二晚20:00与您不见不散！

<专题/报告人征集>

CMOS 2017持续征集专题组织者（在线申请：http://cn.mikecrm.com/82fr4bh）、接收报告人提交摘要（在线投递：http://cn.mikecrm.com/1olN3s6），如果您希望开展某一专题研讨或成为报告人，申请提交后我们会尽快与您取得联系。

<报告人及课题组介绍>

周嘉炜（Jiawei Zhou）received his B.S. in Engineering Mechanics from Tsinghua University, Beijing, China (2013). He is currently pursuing his Ph.D. at Massachusetts Institute of Technology. His interests include fundamental energy transport and their broader applications (thermoelectrics, energy storage, etc). He is currently involved in first principle calculations for the electrical/thermal transport of single-crystal/alloyed bulk materials.

联系邮箱：zhoujw20@mit.edu

MIT NanoEngineering Group：http://web.mit.edu/nanoengineering/

<报告简介>

报告摘要：While the thermoelectric figure of merit zT above 300K has seen significant improvement in recent years, progress in zT at lower temperatures has been slow, mainly limited by the relatively low Seebeck coefficient and high thermal conductivity. In this talk we present our first-principles computation of the phonon drag effect – a coupling phenomenon between electrons and non-equilibrium phonons that has long been regarded as not beneficial for thermoelectric applications – and show that this effect can in fact be exploited to enhance the Seebeck coefficient, while reducing the phonon thermal conductivity. While such trends at first sight seems to be impossible since the high thermal conductivity is also the cause of large phonon drag effect, a key insight we gained from the first-principles simulation is that the phonons contributing to phonon drag and to thermal conductivity do not spectrally overlap. In this light, we examine the effect of an ideal phonon filter on enhancing zT in silicon. By selecting phonons which contribute more to the phonon drag than to the thermal conductivity and filtering out others, zT of silicon at room temperature can be enhanced to ~0.25 and even larger benefit can be gained at lower temperatures. Some practically feasible phonon filters including one using nanocluster scattering are also discussed to achieve such selectivity. We hope this work shows a new approach towards better themoelectrics by harnessing non-equilibrium phonons.