State Key Laboratory of Advanced Technology for Materials Synthesis and Processing , Wuhan University of Technology , Wuhan 430070 , China.
Department of Physics , University of Michigan , Ann Arbor , Michigan 48109 , United States.
ACS Appl Mater Interfaces. 2019 Mar 6;11(9):9197-9204. doi: 10.1021/acsami.8b21524. Epub 2019 Feb 19.
Here we report that CdTe alloying and Sb doping increase the density-of-states effective mass and introduce endotaxial nanostructuring in n-type PbTe, resulting in enhanced thermoelectric performance. A prior theoretical prediction for the presence of resonance states in the conduction band of this system, however, could not be confirmed. An amount of 3 mol % CdTe alloying widens the band gap of PbTe by 50%, leading to enhanced carrier effective mass and Seebeck coefficient. This effect is even more pronounced at high temperatures where the solubility of CdTe increases. At 800 K, when the carrier concentration is the same (4 × 10 cm), the Seebeck coefficient of CdTe-alloyed PbTe is -195 μV K, 16% higher than that of the Cd-free control sample (-168 μV K). Sb doping considerably increases the electron concentration of PbCdTe, giving rise to optimized power factors of ∼17 μW cm K at 800 K. More importantly, Sb induces strained endotaxial nanostructures evenly distributed in the matrix. These Sb-rich nanostructures account for the ∼40% reduction in the lattice thermal conductivity over the whole measured temperature range. As a result, a maximum ZT of 1.2 is attained at 750 K in 0.5 mol % Sb-doped PbCdTe alloys.
在这里，我们报告 CdTe 合金化和 Sb 掺杂可以提高 n 型 PbTe 的态密度有效质量并引入内延纳米结构，从而提高其热电性能。然而，该体系导带中存在共振态的先前理论预测无法得到证实。3 mol%的 CdTe 合金化将 PbTe 的能带隙拓宽了 50%，从而提高了载流子有效质量和 Seebeck 系数。在高温下，CdTe 的溶解度增加，这种效应更加明显。在 800 K 时，当载流子浓度相同时（4×10cm），CdTe 合金化 PbTe 的 Seebeck 系数为-195 μV K，比无 Cd 对照样品（-168 μV K）高 16%。Sb 掺杂大大增加了 PbCdTe 的电子浓度，在 800 K 时产生了优化的功率因子约为 17 μW cm K。更重要的是，Sb 诱导了应变的内延纳米结构均匀分布在基体中。这些富 Sb 的纳米结构使晶格热导率在整个测量温度范围内降低了约 40%。结果，在 0.5 mol% Sb 掺杂的 PbCdTe 合金中，在 750 K 时达到了最大 ZT 值 1.2。
