Band inversion induced multiple electronic valleys for high thermoelectric performance of SnTe with strong lattice softening
Band inversion induced multiple electronic valleys for high thermoelectric performance of SnTe with strong lattice softening
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带反转诱导多个电子谷，实现具有强晶格软化的 SnTe 的高热电性能
DOI：
10.1016/j.nanoen.2019.104395
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发表时间：
2020-03
期刊：
影响因子：
17.6
通讯作者：
Tang Xinfeng
中科院分区：
文献类型：
--
作者：
Xie Guizhen;Li Zhi;Luo Tingting;Bai Hui;Sun Jinchang;Xiao Yu;Zhao Li-Dong;Wu Jinsong;Tan Gangjian;Tang Xinfeng
带状工程作为一种改善热电性能的有效方法正在不断发展。然而，除了设计共振态或带收敛等传统方法外，还没有其他有效的方法来设计电子结构。在这里，在这项研究中，我们展示了一种新的机制，通过将GeTe和PbTe合金化成SnTe，其中由于能带反转效应引入了多个电子谷。SnTe中能带结构的改变导致了塞贝克系数的显著提高。同时，由于晶界处高密度位错产生了强烈的内部污点，导致了显著的晶格软化。晶格软化导致晶格导热系数低。在~873 K时，Sn0.48Cd0.02Ge0.25Pb0.25Te样品的热电系数为meritZT bbb1.4，是原始SnTe样品的两倍。这是首次将多个电子谷引入到SnTe系统带反演中。这种带状结构工程的新方法应该同样适用于其他热电材料。
Band engineering has been under development as an efficient method to improve thermoelectric performance. However, except conventional methods like engineering the resonant states or band convergence, there is still no other effective way to engineer the electronic structure. Here, in this study we demonstrate a new mechanism achieved by alloying GeTe and PbTe into SnTe where multiple electronic valleys are introduced due to band inversion effect. The modification of band structure in SnTe leads to considerable enhancement of Seebeck coefficient. In the meanwhile, GeTe/PbTe coalloying leads to significant lattice softening by intense internal stains, arisen from the high density dislocations at the grain boundaries. The lattice softening leads to a low lattice thermal conductivity. In combination with Cd doping for band gap enlargement, a high thermoelectric figure of meritZT> 1.4 is achieved at ~873 K in the sample Sn0.48Cd0.02Ge0.25Pb0.25Te, which is doubled compared to that of pristine SnTe. It is the first example that multiple electronic valleys are introduced into SnTe systemviaband inversion. This new approach for band structure engineering should be equally applicable to other thermoelectric materials.
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