Zn-Induced Defect Complexity for the High Thermoelectric Performance of n-Type PbTe Compounds
Zn-Induced Defect Complexity for the High Thermoelectric Performance of n-Type PbTe Compounds
复制标题
DOI：
10.1021/acsami.1c14518
复制
发表时间：
2021-09-03
影响因子：
9.5
通讯作者：
Tang, Xinfeng
中科院分区：
文献类型：
--
作者：
Cao, Yu;Bai, Hui;Tang, Xinfeng
虽然缺陷工程是改善热电性能的核心策略，但有效调节设计缺陷的方法有限。在这里，我们证明了一个高的ZT值为1.36在775 K和高的平均ZT值为0.99的温度范围内从300至825 K的含Zn的PbTe通过设计复杂的缺陷实现。通过第一性原理计算和实验相结合，我们表明，Zn原子占据Pb位和间隙位在PbTe和相互耦合。Zn原子在Pb位上的替代引起的收缩应力抵消了Zn原子占据间隙位引起的膨胀应力，促进了间隙Zn原子在PbTe结构中的溶解。Zn杂质作为复合缺陷的稳定化使PbTe相稳定区向Pb 0.995Zn 0.02Te方向扩展，而在三元相图的另一个方向上的固溶区要小得多。通过像差校正扫描透射电子显微镜（Cs校正STEM）和正电子湮没测量进一步明确证实了PbTe中缺陷的演变。Zn原子补偿了Pb空位（V-Pb），Zn杂质（Zn-1）显著提高了电子浓度，使Pb_（0.995）Zn_（0.02）Te样品的载流子迁移率达到1467.7 cm ~（2）V ~（-1）s ~（-1）。Pb 0.995Zn 0.02Te样品在306 K时获得了4.11 mW m（-1）K-2的高功率因数。这项工作为理解n型PbTe中缺陷的性质和演变以及改善电子和热输运性质以实现更高的热电性能提供了新的见解。
Although defect engineering is the core strategy to improve thermoelectric properties, there are limited methods to effectively modulate the designed defects. Herein, we demonstrate that a high ZT value of 1.36 at 775 K and a high average ZT value of 0.99 in the temperature range from 300 to 825 K are realized in Zn-containing PbTe by designing complex defects. By combining first-principles calculations and experiments, we show that Zn atoms occupy both Pb sites and interstitial sites in PbTe and couple with each other. The contraction stress induced via substitutional Zn on Pb sites alleviates the swelling stress by Zn atoms occupying the interstitial sites and promotes the solubility of interstitial Zn atoms in the structure of PbTe. The stabilization of Zn impurity as a complex defect extends the region of PbTe phase stability toward Pb0.995Zn0.02Te, while the solid solution region in the other direction of the ternary phase diagram is much smaller. The evolution of defects in PbTe was further explicitly corroborated by aberration-corrected scanning transmission electron microscopy (Cs-corrected STEM) and positron annihilation measurement. The Zn atoms compensate the Pb vacancies (V-Pb) and Zn interstitials (Zn-i) significantly improve the electron concentration, producing a high carrier mobility of 1467.7 cm(2) V-1 s(-1) for the Pb0.995Zn0.02Te sample. A high power factor of 4.11 mW m(-1) K-2 is achieved for the Pb0.995Zn0.02Te sample at 306 K. This work provides new insights into understanding the nature and evolution of the defects in n-type PbTe as well as improving the electronic and thermal transport properties toward higher thermoelectric performance.