Phonon engineering significantly reducing thermal conductivity of thermoelectric materials: a review

Abstract

Lattice thermal conductivity, $\kappa_{{\text{L}}}$, is a fundamental parameter for evaluating the performance of thermoelectric materials. However, the predicted value of κ_L based on the Debye dispersion model is often overestimated compared with the experimentally determined value. Many researchers have attempted to modify the theoretical model and have sought more reliable results. In this review, the recent progress in the study of phonon dispersion models is summarized and we propose that the lattice thermal conductivity can be most accurately determined by using the modified sinusoidal phonon dispersion model. Moreover, experimental methods that have the potential to reduce a thermoelectric material’s $\kappa_{{\text{L}}}$ are reviewed, for example, methods that generate standing waves or anharmonic lattice vibrations. A high concentration of standing waves and anharmonic lattice vibrations can effectively suppress excessive $\kappa_{{\text{L}}}$. Finally, this review presents the challenges of sinusoidal phonon dispersion when applied to real materials, which are often complicated and therefore time-consuming, especially when dealing with material defects.

Graphical abstract

摘要

晶格导热系数 ($\kappa_{{\text{L}}}$), 是评估热电材料性能的一个基本参数。然而，与实验确定的数值相比，基于德拜扩散模型的预测值往往被高估。许多研究人员试图修改该理论模型, 并寻求更可靠的结果。在这篇综述中，我们总结了声子色散模型研究的最新进展，并提出通过使用修**的**弦声子色散模型可以最准确地确定晶格热导率。此外，本文回顾了有可能降低热电材料 $\kappa_{{\text{L}}}$ 的实验方法, 例如, 产生驻波或非谐波晶格振动的方法。高浓度的驻波和非谐波晶格振动可以有效地抑制过度的 $\kappa_{{\text{L}}}$。最后，本综述介绍了**弦声子色散在应用于实际材料时面临的挑战，这些材料往往很复杂, 因此很费时间，特别是在处理材料缺陷时。