Qi Xia, Kang Te, Yang Long, Zhang Xinyue, Luo Jun, Li Wen, Pei Yanzhong
Interdisciplinary Materials Research Center, School of Materials Science and Engineering, Tongji University, 4800 Caoan Road, Shanghai, 201804, China.
State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai, 200050, China.
Adv Sci (Weinh). 2024 Dec;11(47):e2407413. doi: 10.1002/advs.202407413. Epub 2024 Nov 17.
Superior electronic performance due to the highly degenerated Σ valence band (N∼12) makes rhombohedral GeTe a promising low-temperature (<600 K) thermoelectric candidate. Minimizing lattice thermal conductivity (κ) is an essential route for enhancing thermoelectric performance, but the temperature-dependent κ, corelated to T, makes its reduction difficult at low temperature. In this work, a room-temperature κ of ≈0.55 W m-K, the lowest ever reported in GeTe-based thermoelectric, is realized in (Ge SbTe) (CuGeSe), primarily due to strong phonon scattering induced by point defects and precipitates. Simultaneously, CuGeSe-alloying effectively suppresses the precipitation of Ge, enabling the optimization of carrier concentration with the additional help of aliovalent Sb doping. As a result, an extraordinary peak zT of up to 2.3 and an average zT of ≈1.2 within 300-625 K are achieved, leading to a conversion efficiency of ≈9% at a temperature difference of 282 K. This work robustly demonstrates its potential as a promising component in thermoelectric generator utilizing low-grade waste heat.
由于高度简并的Σ价带（N∼12），菱方相GeTe具有优异的电子性能，使其成为一种有前景的低温（<600 K）热电候选材料。降低晶格热导率（κ）是提高热电性能的关键途径，但与温度相关的κ使得在低温下降低它变得困难。在这项工作中，（GeSbTe）（CuGeSe）实现了室温下κ≈0.55 W m⁻¹K⁻¹，这是基于GeTe的热电材料中报道的最低值，主要归因于点缺陷和析出物引起的强烈声子散射。同时，CuGeSe合金化有效地抑制了Ge的析出，在异价Sb掺杂的额外帮助下实现了载流子浓度的优化。结果，在300 - 625 K范围内实现了高达2.3的异常峰值zT和约1.2的平均zT，在282 K的温差下转换效率约为9%。这项工作有力地证明了其作为利用低品位废热的热电发电机中有前景的组件的潜力。
