First-principles study of mechanical, electronic and optical properties of Janus structure in transition metal dichalcogenides
First-principles study of mechanical, electronic and optical properties of Janus structure in transition metal dichalcogenides
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DOI：
10.1016/j.apsusc.2020.146730
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发表时间：
2020-10-01
影响因子：
6.7
通讯作者：
Hung, Nguyen Tuan
中科院分区：
文献类型：
--
作者：
Thanh, Vuong Van;Van, Nguyen Duy;Hung, Nguyen Tuan
用第一性原理计算方法研究了过渡金属二卤化物(TMDs)单层结构Mxy(M=Mo，W；X或Y=S，Se，Te；X不等于Y)的力学、电学和光学性质，其中TMDs两侧的硫族原子是不同的元素。我们的计算结果表明，由于其最强的离子键，WSSe在Janus TMD中显示出最高的硬度和最理想的强度。在无应变情况下，WSeTe、WSSe和MoSeTe是直接带隙半导体，而MoSe、MoSTe和WSTe是间接带隙半导体。由于X/Y和M原子的p和d轨道之间的耦合，Janus TMD的能带隙随着拉伸应变的增加而减小。此外，拉伸应变有效地调制了Janus TMD的光吸收。例如，当光子能量为2.5 eV时，Mosse的光吸收要强三倍。Janus TMD的计算结果为纳米机电、光电子学和光催化器件的应用提供了有用的信息。
Using first-principles calculations, we investigate mechanical, electronic and optical properties of so-called Janus structure for monolayer transition metal dichalcogenides (TMDs), MXY (M = Mo, W; X or Y = S, Se, Te; X not equal Y), in which chalcogen atoms at both side of the TMDs are not the same elements. Our calculated results indicate that WSSe shows the highest stiffness and the most ideal strength among the Janus TMDs due to their strongest ionic bond. In the unstrain cases, WSeTe, WSSe and MoSeTe are direct-gap semiconductors, while MoSSe, MoSTe and WSTe are indirect-gap semiconductors. The energy band gaps of the Janus TMDs decrease with increasing of the tensile strain due to the coupling between the p and d orbitals of the X/Y and M atoms, respectively. Furthermore, the tensile strain effectively modulates the optical absorption of the Janus TMDs. For example, the optical absorption of MoSSe is three times stronger at a photon energy of 2.5 eV. The calculated results of Janus TMDs provide useful information for applications in nanoelecromechanical, optoelectronic, and photocatalyst devices.