Grain-Size-Controlled Mechanical Properties of Polycrystalline Monolayer MoS2

• DOI: 10.1021/acs.nanolett.7b05433
• Publication Date: 2018-02-01T22:02:42Z
• Authors: Jianyang Wu; Pinqiang Cao; Zhisen Zhang; Fulong Ning; Song-sheng Zheng; Jianying He; Zhiliang Zhang
• Keywords: 02 engineering and technology; 0210 nano-technology

Pristine monocrystalline molybdenum disulfide (MoS2) possesses high mechanical strength comparable to that of stainless steel. Large-area chemical-vapor-deposited monolayer MoS2 tends be polycrystalline with intrinsic grain boundaries (GBs). Topological defects and size skillfully alter its physical properties in a variety materials; however, the polycrystallinity role played performance emerging single-layer remain largely unknown. Here, using large-scale atomistic simulations, GB structures characteristics realistic single-layered varying prepared by confinement-quenched method are investigated. Depending on misorientation angle, structural energetics polar-GBs polycrystals favor diverse dislocation cores, consistent experimental observations. Polycrystals exhibit grain-size-dependent thermally induced global out-of-plane deformation, although defective GBs show planar contrast graphene. Tensile tests presence cohesive pronouncedly deteriorates in-plane MoS2. Both stiffness follow an inverse pseudo Hall-Petch relation size, which is shown governed weakest link mechanism. Under uniaxial tension, transgranular crack propagates small deflection, whereas upon biaxial stretching, grows kinked manner large deflection. These findings shed new light GB-based engineering control crystals toward real-world applications flexible electronics nanoelectromechanical systems.