Ultralow Lattice Thermal Conductivity and Superhigh Thermoelectric Figure-of-Merit in (Mg, Bi) Co-Doped GeTe
Ultralow Lattice Thermal Conductivity and Superhigh Thermoelectric Figure-of-Merit in (Mg, Bi) Co-Doped GeTe
复制标题
DOI：
10.1002/adma.202008773
复制
发表时间：
2021-03-24
影响因子：
29.4
通讯作者：
Chen, Lidong
中科院分区：
文献类型：
--
作者：
Xing, Tong;Zhu, Chenxi;Chen, Lidong
热电材料的性能决定了热电技术的高效性。掺杂是TE中实现优化的电性能和降低的热导率的常规方法。然而，如何选择合适的掺杂剂与所需的溶液含量，以实现高的TE优值（zT）是非常坚韧的工作。在这项研究中，通过使用大的质量和应变场波动作为低晶格热导率的指标，GeTe中（Mg，Bi）的组合被筛选为非常有效的掺杂剂，用于潜在的高zTs。在实验中，制备了一系列（Mg，Bi）共掺杂GeTe化合物，并系统地研究了其电输运和热输运性质。Ge_（0.9）Mg_（0.04）Bi_（0.06）Te的晶格热导率在600 K时约为0.3 W m（-1）K-1，这是由于（Mg，Bi）共掺杂引入了大的质量场和应变场起伏。此外，（Mg，Bi）共掺杂可以引入额外的电子以获得最佳的载流子浓度，并减小价带顶部的能量偏移以获得高的态密度有效质量。通过这些合成效应，Ge_（0.9）Mg_（0.04）Bi_（0.06）Te在700 K时获得了约2.5的超高zT。该研究为其他TE材料中有效掺杂剂的合理设计提供了参考。
High-efficiency thermoelectric (TE) technology is determined by the performance of TE materials. Doping is a routine approach in TEs to achieve optimized electrical properties and lowered thermal conductivity. However, how to choose appropriate dopants with desirable solution content to realize high TE figure-of-merit (zT) is very tough work. In this study, via the use of large mass and strain field fluctuations as indicators for low lattice thermal conductivity, the combination of (Mg, Bi) in GeTe is screened as very effective dopants for potentially high zTs. In experiments, a series of (Mg, Bi) co-doped GeTe compounds are prepared and the electrical and thermal transport properties are systematically investigated. Ultralow lattice thermal conductivity, about 0.3 W m(-1) K-1 at 600 K, is obtained in Ge0.9Mg0.04Bi0.06Te due to the introduced large mass and strain field fluctuations by (Mg, Bi) co-doping. In addition, (Mg, Bi) co-doping can introduce extra electrons for optimal carrier concentration and diminish the energy offset at the top of the valence band for high density-of-states effective mass. Via these synthetic effects, a superhigh zT of approximate to 2.5 at 700 K is achieved for Ge0.9Mg0.04Bi0.06Te. This study sheds light on the rational design of effective dopants in other TE materials.