Shenzhen Key Laboratory of Thermoelectric Materials, Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China.
School of Materials and Energy, University of Electronic Science and Technology of China, Chengdu 610054, China.
Science. 2022 Jul 8;377(6602):208-213. doi: 10.1126/science.abq5815. Epub 2022 Jul 7.
The high-entropy concept provides extended, optimized space of a composition, resulting in unusual transport phenomena and excellent thermoelectric performance. By tuning electron and phonon localization, we enhanced the figure-of-merit value to 2.7 at 750 kelvin in germanium telluride-based high-entropy materials and realized a high experimental conversion efficiency of 13.3% at a temperature difference of 506 kelvin with the fabricated segmented module. By increasing the entropy, the increased crystal symmetry delocalized the distribution of electrons in the distorted rhombohedral structure, resulting in band convergence and improved electrical properties. By contrast, the localized phonons from the entropy-induced disorder dampened the propagation of transverse phonons, which was the origin of the increased anharmonicity and largely depressed lattice thermal conductivity. We provide a paradigm for tuning electron and phonon localization by entropy manipulation, but we have also demonstrated a route for improving the performance of high-entropy thermoelectric materials.
高熵概念提供了组成的扩展和优化空间，从而产生了异常的输运现象和优异的热电性能。通过调整电子和声子的局域化，我们将碲化锗基高熵材料的品质因数值提高到 750 开尔文时的 2.7，并在 506 开尔文的温差下利用制造的分段模块实现了 13.3%的高实验转换效率。通过增加熵，增加的晶体对称性使电子在扭曲的三方结构中的分布去局域化，导致能带收敛和电性能改善。相比之下，熵引起的无序产生的局域声子会抑制横向声子的传播，这是增加非谐性和大幅降低晶格热导率的原因。我们提供了一种通过熵操纵来调整电子和声子局域化的范例，但我们也证明了一种提高高熵热电材料性能的途径。
