Achieving high-performance n-type PbTe via synergistically optimizing effective mass and carrier concentration and suppressing lattice thermal conductivity,Chemical Engineering Journal

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Achieving high-performance n-type PbTe via synergistically optimizing effective mass and carrier concentration and suppressing lattice thermal conductivity
Chemical Engineering Journal ( IF 13.3 ) Pub Date : 2021-09-24 , DOI: 10.1016/j.cej.2021.132601
Hang-Tian Liu ₁ , Qiang Sun _{2,

3} , Yan Zhong ₁ , Cheng-Liang Xia ₄ , Yue Chen ₄ , Zhi-Gang Chen _{2,

5} , Ran Ang _{1,

6}

Affiliation

Introducing resonant levels is a potent strategy to improve the thermoelectric properties of the thermoelectric systems. However, the beneficial effect of resonant levels tends to be weakened with rising temperature for the PbTe system. This motivates us to introduce dynamic doping of Cu into Cr-doped n-type PbTe to achieve the fully optimized carrier transport over a wide temperature range. As a consequence, an extraordinary figure of merit, of ∼ 0.55 at room temperature, a peak of ∼ 1.31 at 773 K and an average of ∼ 1.02 in the range of 323 to 823 K are obtained in the PbCrTe-0.2%Cu. Additionally, how co-doped of Cr and Cu contributes to suppressing thermal transports is still ambiguous. Herein, we employ comprehensive electron microscopy investigations to reveal that the synergistic incorporation of Cr and Cu into the PbTe matrix results in a series of phonon scattering sources, including massive point defects, high-density of nanoscale precipitates, microscale secondary phases, and dense grain boundaries, which can significantly reduce the lattice thermal conductivity by enhancing phonon scattering. This work clarifies the fundamental Cr-doping mechanism in PbTe and demonstrates that dynamic Cu-doping engineering is an effective approach to boosting thermoelectric performance, which should be applied in other thermoelectric materials.

中文翻译：

通过协同优化有效质量和载流子浓度以及抑制晶格热导率实现高性能 n 型 PbTe

引入谐振水平是提高热电系统热电性能的有效策略。然而，随着 PbTe 系统温度的升高，谐振能级的有益效果往往会减弱。这促使我们将 Cu 动态掺杂到 Cr 掺杂的 n 型 PbTe 中，以在较宽的温度范围内实现完全优化的载流子传输。因此，PbCrTe-0.2%Cu 获得了非凡的品质因数，室温下约为 0.55，773 K 时峰值约为 1.31，323 至 823 K 范围内的平均值约为 1.02。此外，Cr 和 Cu 的共掺杂如何有助于抑制热传输仍然不清楚。在此，我们采用全面的电子显微镜研究揭示了 Cr 和 Cu 协同掺入 PbTe 基体中导致了一系列声子散射源，包括大量点缺陷、高密度纳米级析出物、微米级第二相和致密晶粒边界，可以通过增强声子散射来显着降低晶格热导率。这项工作阐明了 PbTe 中 Cr 掺杂的基本机制，并证明动态 Cu 掺杂工程是提高热电性能的有效方法，应该应用于其他热电材料。

更新日期：2021-09-24

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