Geometry and Greatly Enhanced Thermoelectric Performance of Monolayer MXY Transition-Metal Dichalcogenide: MoSTe as an Example,Physica Status Solidi-Rapid Research Letters

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Geometry and Greatly Enhanced Thermoelectric Performance of Monolayer MXY Transition-Metal Dichalcogenide: MoSTe as an Example
Physica Status Solidi-Rapid Research Letters ( IF 2.5 ) Pub Date : 2021-06-01 , DOI: 10.1002/pssr.202100166
Zhenyu Ding _{1,

2} , Shuo-Wang Yang ₃ , Gang Wu ₃ , Xiaoping Yang _{1,

4}

Affiliation

2D thermoelectric materials with a high power factor and low lattice thermal conductivity have recently been the focus of cutting-edge research. Herein, combining first-principles calculations and semiclassical Boltzmann transport theory, a structural search on the monolayer transition-metal dichalcogenide MoSTe is conducted and its electronic structure, lattice dynamics, and thermoelectric properties are carefully studied. A new tetragonal blend structure is found that is both energetically and dynamically more stable than the experimentally synthesized hexagonal Janus structure, and this blend structure possesses strong anisotropic in-plane electron and phonon transport properties. Both structures have insulating ground states, which allow a reasonable Seebeck coefficient. Phonon dispersion reveals that several optical phonon-branches downshift and overlap with the acoustic branches, leading to an enhanced scattering rate, greatly reduced lattice thermal conductivity, and eventually excellent thermoelectric performance with

Z T

= 0.34 at 300 K and 1.0 at 600 K for the blend-MoSTe. The results demonstrate the great potential of the monolayer MXY transition-metal dichalcogenide in thermoelectric applications.

中文翻译：

单层 MXY 过渡金属二硫属化物的几何形状和显着增强的热电性能：以 MoSTe 为例

具有高功率因数和低晶格热导率的二维热电材料最近成为前沿研究的焦点。在此，结合第一性原理计算和半经典玻尔兹曼输运理论，对单层过渡金属二硫族化合物 MoSTe 进行了结构搜索，并对其电子结构、晶格动力学和热电性质进行了仔细研究。发现了一种新的四方混合结构，它在能量和动力学上都比实验合成的六方 Janus 结构更稳定，并且这种混合结构具有很强的各向异性面内电子和声子传输特性。两种结构都具有绝缘基态，这允许合理的塞贝克系数。