Bera Jayanta, Sahu Satyajit
Department of Physics, Indian Institute of Technology Jodhpur Jodhpur 342037 India
RSC Adv. 2019 Aug 13;9(43):25216-25224. doi: 10.1039/c9ra04470a. eCollection 2019 Aug 8.
Two-dimensional transition metal dichalcogenides show great potential as promising thermoelectric materials due to their lower dimensionality, the unique density of states and quantum confinement of carriers. Here the effects of mechanical strain on the thermoelectric performances of monolayer WS have been investigated using density functional theory associated with semiclassical Boltzmann transport theory. The variation of the Seebeck coefficient and band gap with applied strain has followed the same type of trend. For n-type material the relaxation time scaled power factor ( /) increases by the application of compressive strain whereas for p-type material it increases with the application of tensile strain due to valley degeneracy. A 77% increase in the power factor has been observed for the n-type material by the application of uniaxial compressive strain. A decrease in lattice thermal conductivity with the increase in temperature causes an almost 40% increase in product under applied uniaxial compressive strain. From the study, it is observed that uniaxial compressive strain is more effective among all types of strain to enhance the thermoelectric performance of monolayer WS. Such strain induced enhancement of thermoelectric properties in monolayer WS could open a new window for the fabrication of high-quality thermoelectric devices.
二维过渡金属二硫属化物因其较低的维度、独特的态密度和载流子的量子限制，作为有前景的热电材料显示出巨大潜力。在此，利用与半经典玻尔兹曼输运理论相关的密度泛函理论，研究了机械应变对单层WS热电性能的影响。塞贝克系数和带隙随施加应变的变化遵循相同类型的趋势。对于n型材料，通过施加压缩应变，弛豫时间缩放功率因子（ /）增加，而对于p型材料，由于谷简并，它随拉伸应变的施加而增加。通过施加单轴压缩应变，n型材料的功率因子提高了77%。随着温度升高，晶格热导率降低，在施加单轴压缩应变的情况下， 乘积几乎增加了40%。从研究中观察到，在所有类型的应变中，单轴压缩应变对于提高单层WS的热电性能更为有效。这种应变诱导的单层WS热电性能增强可为高质量热电器件的制造打开一扇新窗口。
