Abstract：Thermoelectrics enable direct heat-to-electricity transformation, but their performance has so far been restricted by the closely coupled electron and phonon transport. The figure of merit, ZT, is the essential measure of thermoelectric performance and can be calculated by ZT = S²σT/κ, where S, σ, κ, and T are Seebeck coefficient, electrical conductivity, total thermal conductivity and absolute temperature, respectively. Although established strategies to optimize ZT usually treat electrical and thermal properties separately, enhancing ZT requires simultaneous optimization of the adversely interdependent S, σ, and κ, which is challenging because most crystal imperfections are believed to scatter both phonons and electrons. This presentation will show that the power factor (S²σ) can be boosted by trap hole release and energy-band engineering including band convergence. The total thermal conductivity can be suppressed by the introduction of all scale defects, high entropy, quantum gap and so on, which provide general methods for boosting their thermoelectric performance. It will also illustrate three examples（PbQ^{1, 2}, GeTe^3,4, and AgCrSe₂⁵）of emerging excitements in nanostructured materials and systems for thermoelectric materials. It will highlight the role of advanced and classical electron microscopy in unravelling the hierarchical architecture of the constituents and their intimate interplay in governing key phenomena in thermoelectric materials.

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报告人简介：何佳清, 南方科技大学物理系讲席教授, 美国物理学会会士(APS fellow)；1998年获得武汉大学物理学学士学位；2004年获得武汉大学和德国于利希研究中心联合培养的物理学博士学位；2004-2012年先后在美国布鲁克海文国家实验室和西北大学工作。主要从事透射电子显微镜、热电材料与器件物理、结构与性能关联性领域的科学研究。已发表包括Science/Nature(11篇, 5篇通讯)等高水平SCI期刊论文300余篇；总引用近42000次，H因子96。