Subtle Roles of Sb and S in Regulating the Thermoelectric Properties of N‐Type PbTe to High Performance
Subtle Roles of Sb and S in Regulating the Thermoelectric Properties of N‐Type PbTe to High Performance
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DOI：
10.1002/aenm.201700099
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发表时间：
2017-05
影响因子：
27.8
通讯作者：
G. Tan;C. Stoumpos;Si Wang;T. Bailey;Li-dong Zhao;C. Uher;M. Kanatzidis
中科院分区：
文献类型：
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作者：
G. Tan;C. Stoumpos;Si Wang;T. Bailey;Li-dong Zhao;C. Uher;M. Kanatzidis
报道了通过分别掺入Sb和S对n型PbTe的电学和热学性能进行改性，使其在900K时具有较高的热电优值≈1.4.Sb被确认为PbTe中的两性掺杂剂，在低掺杂水平(<；1%)填充Te空位，超过该水平则进入PbTe位。研究发现，掺Sb的PbTe材料比类似的掺铋材料具有更高的载流子迁移率，从而提供了更高的功率因数和更好的ZT。电子输运的增强归因于Te空位的消除，Te空位似乎强烈地散射n型载流子。在此基础上，通过在Te亚晶格中合金化S，进一步提高了Pb0.9875Sb0.0125Te的ZT。S的引入打开了PbTe的禁带，抑制了双极导电，同时提高了电子浓度和电导率。此外，它还引入了点缺陷并诱导了第二相纳米结构，使该材料在900K时的晶格热导率降至≈0.5W m−1K−1，使其成为高温(500-900K)热电应用的候选材料。预计这里提供的见解将是对不断增长的优化热电材料性能的战略武器库的重要补充。
A high ZT (thermoelectric figure of merit) of ≈1.4 at 900 K for n‐type PbTe is reported, through modifying its electrical and thermal properties by incorporating Sb and S, respectively. Sb is confirmed to be an amphoteric dopant in PbTe, filling Te vacancies at low doping levels (<1%), exceeding which it enters into Pb sites. It is found that Sb‐doped PbTe exhibits much higher carrier mobility than similar Bi‐doped materials, and accordingly, delivers higher power factors and superior ZT. The enhanced electronic transport is attributed to the elimination of Te vacancies, which appear to strongly scatter n‐type charge carriers. Building on this result, the ZT of Pb0.9875Sb0.0125Te is further enhanced by alloying S into the Te sublattice. The introduction of S opens the bandgap of PbTe, which suppresses bipolar conduction while simultaneously increasing the electron concentration and electrical conductivity. Furthermore, it introduces point defects and induces second phase nanostructuring, which lowers the lattice thermal conductivity to ≈0.5 W m−1 K−1 at 900 K, making this material a robust candidate for high‐temperature (500–900 K) thermoelectric applications. It is anticipated that the insights provided here will be an important addition to the growing arsenal of strategies for optimizing the performance of thermoelectric materials.