Cao Wei, Wang Ziyu, Miao Ling, Shi Jing, Xiong Rui
Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, P. R. China.
The Institute of Technological Sciences, Wuhan University, Wuhan 430072, P. R. China.
ACS Appl Mater Interfaces. 2021 Jul 28;13(29):34367-34373. doi: 10.1021/acsami.1c08686. Epub 2021 Jul 20.
In recent years, the high-temperature phase of CuSe, namely, β-CuSe, has attracted increasing attention due to its outstanding thermoelectric efficiency. The Cu ions in β-CuSe show a distinct ion-liquid behavior between the framework of a Se ion lattice. Many experimental operations may lead to a discrepancy in the lattice structure. Experimentally synthesized β-CuSe was p-type, and a thermoelectric device needs both p-type and n-type materials with a close figure of merit. Studying the effect of strain and the possibility of n-type β-CuSe is essential. Utilizing first-principles calculations and molecular dynamics simulations, we investigate the thermoelectric performance of strained β-CuSe. The results show that the n-type β-CuSe can exhibit superior values like the p-type one. Applying compressive strain is an effective way to promote the power factor. The tensile strain will lead to a low lattice thermal conductivity and thus boost the p-type values. The predicted maximum values for n-type and p-type β-CuSe can reach 1.65 and 1.71 at 800 K, respectively. Considering the fact that applying strain is challenging in experiments, we propose a feasible strategy to manipulate the lattice structure and carrier type: doping halogen elements. Our results provide a guide for CuSe-based thermoelectric devices.
近年来，CuSe的高温相，即β - CuSe，因其出色的热电效率而受到越来越多的关注。β - CuSe中的铜离子在硒离子晶格框架之间表现出独特的离子液体行为。许多实验操作可能会导致晶格结构出现差异。实验合成的β - CuSe是p型的，而热电装置需要具有相近优值的p型和n型材料。研究应变的影响以及n型β - CuSe的可能性至关重要。利用第一性原理计算和分子动力学模拟，我们研究了应变β - CuSe的热电性能。结果表明，n型β - CuSe可以表现出与p型相当的优异值。施加压缩应变是提高功率因子的有效方法。拉伸应变会导致较低的晶格热导率，从而提高p型的优值。预测在800 K时，n型和p型β - CuSe的最大优值分别可达1.65和1.71。考虑到在实验中施加应变具有挑战性，我们提出了一种操纵晶格结构和载流子类型的可行策略：掺杂卤素元素。我们的结果为基于CuSe的热电装置提供了指导。
