Two-dimensional MoS₂ electromechanical actuators

Abstract

We investigate electromechanical properties of two-dimensional MoS 2 monolayers in the 1H, 1T, and 1T structures as a function of charge doping by using density functional theory. We find isotropic elastic moduli in the 1H and 1T structures, while the 1T structure exhibits an anisotropic elastic modulus. Moreover, the 1T structure is shown to have a negative Poisson's ratio, while Poisson's ratios of the 1H and 1T are positive. By charge doping, the monolayer MoS 2 shows a reversibly strain and work density per cycle ranging from −0.68% to 2.67% and from 4.4 to 36.9 MJ/m 3 , respectively, making them suitable for applications in electromechanical actuators. Stress generated is also examined in this work and we find that 1T and 1T MoS 2 monolayers relatively have better performance than 1H MoS 2 monolayer. We argue that such excellent electromechanical performance originate from the electrical conductivity of the metallic 1T and semimetallic 1T structures high Young's modulus of about 150 − 200 GPa. arXiv:1711.00188v1 [cond-mat.mtrl-sci] 1 Nov 2017 Two-dimensional MoS 2 electromechanical actuators

Mechanical Properties of Monolayer MoS2 with Randomly Distributed Defects

“…Li et al [16] performed MD simulation under the uniaxial test presented that C 11 is found to be 199 GPa for the 1H MoS 2 , our results are while Nguyen T.H. [25] obtained an average young's modulus of 201 GPa for monolayer MoS 2 . Note the deviation due to the performed DFT calculations, which are derived from the finite difference approach by Thermo-pw code, and we have used latest SW potential which can be used for higher temperatures as well.…”

“…This information helps to interpret the mechanisms by which the defects alter the properties of MoS 2 . Independent elastic constants by using density functional theory are well described by Nguyen T. Hung [25] as they concentrate on electromechanical properties both 1H and 1T MoS 2 monolayer as a role of charge doping.…”

Charge-induced electromechanical actuation of Mo- and W-dichalcogenide monolayers

“…They form the distorted 1T structure, namely 1T 0 structure. 31 Since the MX 2 monolayers with 1T 0 structure exhibit an anisotropic behavior, 12,31 in present study, we only focus on the isotropic 1H-and 1T-MX 2 monolayers.…”

“…However, their study has limited to the MoS 2 nanosheets with only 1T structure. By using the density functional theory (DFT) calculations, Hung et al 12 investigated the actuator performance of the MoS 2 monolayer with the 1H, 1T and 1T 0 structures. They pointed out that the actuator performance of the MoS 2 monolayers with the 1T and 1T 0 structures are better than that of the 1H structure.…”

“…This because the interplay between the actuation strain and Young's modulus of the MoS 2 monolayer with difference structures. Both experiment and theory 11,12 only focused of the MoS 2 monolayer actuator, while the actuator properties of other TMDs are not fully explored yet, except for some limited experiments. 13 In this sense, a systematic theoretical design of many TMDs materials could be the rst step to suggest possible structures suitable as highest electromechanical actuators.…”