Approaching Topological Insulating States Leads to High Thermoelectric Performance in n-Type PbTe
Approaching Topological Insulating States Leads to High Thermoelectric Performance in n-Type PbTe
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接近拓扑绝缘态导致 n 型 PbTe 具有高热电性能
DOI：
10.1021/jacs.8b09029
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发表时间：
2018
影响因子：
15
通讯作者：
Zhao Li Dong
中科院分区：
文献类型：
--
作者：
Xiao Yu;Wang Dongyang;Qin Bingchao;Wang Jinfeng;Wang Guangtao;Zhao Li Dong
实现高热电性能需要高的电输运性能和低的导热系数，这本质上是通过平衡载流子迁移率、有效质量和晶格导热系数三者之间相互依赖的争议来决定的。在这里，我们观察到Sn和Se共合金PbTe的电子能带反转（接近拓扑绝缘状态），从而优化了有效质量和载流子迁移率。在PbTe（Se）中加入Sn合金，由于能带反转，可以缩小其带隙，并诱导出更锐利的导带（等于更低的载流子质量），这进一步促进了高载流子迁移率，在室温下，pb0.89 sn0.11 te0.89 se0.11为251cm2v - 1s - 1in，从而实现了高功率因数。同时，我们发现通过Sn和Se共合金化产生点缺陷，晶格热导率可从~ 0.77 Wm-1K-1in PbTe降至~ 0.45 Wm-1K-1in (Pb0.91Sn0.09)（Te0.91Se0.09）。通过电子能带反演，我们得到了n型（Pb0.93Sn0.07）（Te0.93Se0.07）在773 K时的最大zt值~ 1.4。
Realizing high thermoelectric performance requires high electrical transport properties and low thermal conductivity, which are essentially determined by balancing the interdependent controversy of carrier mobility, effective mass, and lattice thermal conductivity. Here, we observed an electronic band inversion (approaching topological insulating states) in Sn and Se co-alloyed PbTe, resulting in optimizing effective mass and carrier mobility. The Sn alloying in PbTe(Se) can narrow its band gap due to band inversion and induce a sharper conduction band (equals to lower carrier mass), which further facilitates high carrier mobility, ∼251 cm2V–1s–1in Pb0.89Sn0.11Te0.89Se0.11at room temperature, thus leading to a high power factor. Meanwhile, we found that the lattice thermal conductivity κlcan be reduced from ∼0.77 Wm–1K–1in PbTe to ∼0.45 Wm–1K–1in (Pb0.91Sn0.09)(Te0.91Se0.09) by producing point defects via Sn and Se co-alloying. Coupling reducing lattice thermal conductivity with integration of optimizing effective mass and carrier mobility by means of electronic band inversion, we obtained a maximumZTvalue ∼1.4 at 773 K in n-type (Pb0.93Sn0.07)(Te0.93Se0.07).