scholarly journals Differences in the Mechanical Properties of Monolayer and Multilayer WSe2/MoSe2

MRS Advances ◽  
2018 ◽  
Vol 3 (6-7) ◽  
pp. 373-378
Author(s):  
Y. M. Jaques ◽  
P. Manimunda ◽  
Y. Nakanishi ◽  
S. Susarla ◽  
C. F. Woellner ◽  
...  

ABSTRACTTransition metal dichalcogenides are 2D structures with remarkable electronic, chemical, optical and mechanical properties. Monolayer and crystal properties of these structures have been extensively investigated, but a detailed understanding of the properties of their few-layer structures are still missing. In this work we investigated the mechanical differences between monolayer and multilayer WSe2 and MoSe2, through fully atomistic molecular dynamics simulations (MD). It was observed that single layer WSe2/MoSe2 deposited on silicon substrates have larger friction coefficients than 2, 3 and 4 layered structures. For all considered cases it is always easier to peel off and/or to fracture MoSe2 structures. These results suggest that the interactions between first layer and substrate are stronger than interlayer interactions themselves. Similar findings have been reported for other nanomaterials and it has been speculated whether this is a universal-like behavior for 2D layered materials. We have also analyzed fracture patterns. Our results show that fracture is chirality dependent with crack propagation preferentially perpendicular to W(Mo)-Se bonds and faster for zig-zag-like defects.

Author(s):  
Manoj K. Jana ◽  
C. N. R. Rao

The discovery of graphene marks a major event in the physics and chemistry of materials. The amazing properties of this two-dimensional (2D) material have prompted research on other 2D layered materials, of which layered transition metal dichalcogenides (TMDCs) are important members. Single-layer and few-layer TMDCs have been synthesized and characterized. They possess a wide range of properties many of which have not been known hitherto. A typical example of such materials is MoS 2 . In this article, we briefly present various aspects of layered analogues of graphene as exemplified by TMDCs. The discussion includes not only synthesis and characterization, but also various properties and phenomena exhibited by the TMDCs. This article is part of the themed issue ‘Fullerenes: past, present and future, celebrating the 30th anniversary of Buckminster Fullerene’.


2021 ◽  
Author(s):  
Ali Sheraz ◽  
Naveed Mehmood ◽  
Mert Mirac Cicek ◽  
İbrahim Ergün ◽  
Hamid Reza Rasouli ◽  
...  

Mechanical properties of transition metal dichalcogenides (TMDCs) are relevant to their prospective applications in flexible electronics. So far, the focus has been on the semiconducting TMDCs, mostly MoX2 and WX2...


Nanoscale ◽  
2021 ◽  
Author(s):  
Jianchen Lu ◽  
Gefei Niu ◽  
Xiao Ren ◽  
De-Liang Bao ◽  
Hui Chen ◽  
...  

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are emerging as new electrocatalysts and photocatalysts, in which edge sites of 2D TMDs are highly catalytic activity and are thus favored at the...


2016 ◽  
Vol 18 (34) ◽  
pp. 23695-23701 ◽  
Author(s):  
Bohayra Mortazavi ◽  
Alireza Ostadhossein ◽  
Timon Rabczuk ◽  
Adri C. T. van Duin

Mechanical properties of all-MoS2 single-layer structures at room temperature are explored using ReaxFF simulations.


Nanophotonics ◽  
2018 ◽  
Vol 7 (10) ◽  
pp. 1589-1600 ◽  
Author(s):  
M.A. Khan ◽  
Michael N. Leuenberger

AbstractThe discovery of two-dimensional (2D) materials has opened up new frontiers and challenges for exploring fundamental research. Recently, single-layer (SL) transition metal dichalcogenides (TMDCs) have emerged as candidate materials for electronic and optoelectronic applications. In contrast to graphene, SL TMDCs have sizable band gaps that change from indirect to direct in SLs, which is useful in making thinner and more efficient electronic devices, such as transistors, photodetectors, and electroluminescent devices. In addition, SL TMDCs show strong spin-orbit coupling effects at the valence band edges, giving rise to the observation of valley-selective optical excitations. Here, we review the basic electronic and optical properties of pure and defected group-VIB SL TMDCs, with emphasis on the strong excitonic effects and their prospect for future optoelectronic devices.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Chiara Trovatello ◽  
Florian Katsch ◽  
Nicholas J. Borys ◽  
Malte Selig ◽  
Kaiyuan Yao ◽  
...  

Abstract The equilibrium and non-equilibrium optical properties of single-layer transition metal dichalcogenides (TMDs) are determined by strongly bound excitons. Exciton relaxation dynamics in TMDs have been extensively studied by time-domain optical spectroscopies. However, the formation dynamics of excitons following non-resonant photoexcitation of free electron-hole pairs have been challenging to directly probe because of their inherently fast timescales. Here, we use extremely short optical pulses to non-resonantly excite an electron-hole plasma and show the formation of two-dimensional excitons in single-layer MoS2 on the timescale of 30 fs via the induced changes to photo-absorption. These formation dynamics are significantly faster than in conventional 2D quantum wells and are attributed to the intense Coulombic interactions present in 2D TMDs. A theoretical model of a coherent polarization that dephases and relaxes to an incoherent exciton population reproduces the experimental dynamics on the sub-100-fs timescale and sheds light into the underlying mechanism of how the lowest-energy excitons, which are the most important for optoelectronic applications, form from higher-energy excitations. Importantly, a phonon-mediated exciton cascade from higher energy states to the ground excitonic state is found to be the rate-limiting process. These results set an ultimate timescale of the exciton formation in TMDs and elucidate the exceptionally fast physical mechanism behind this process.


ACS Nano ◽  
2019 ◽  
Vol 13 (5) ◽  
pp. 5611-5615
Author(s):  
Peng Chen ◽  
Yun-Ting Chen ◽  
Ro-Ya Liu ◽  
Han-De Chen ◽  
Dengsung Lin ◽  
...  

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