Stacking order dependent mechanical properties of graphene/MoS2 bilayer and trilayer heterostructures

Transition metal dichalcogenides (TMDC) such as molybdenum disulfide (MoS2) are two-dimensional materials that show promise for flexible electronics and piezoelectric applications, but their weak mechanical strength is a barrier to practical use. In this work, we perform nanoindentation simulations using atomistic molecular dynamics to study the mechanical properties of heterostructures formed by combining MoS2 with graphene. We consider both bi- and tri-layer heterostructures formed with MoS2 either supported or encapsulated by graphene. Mechanical properties, such as Young's modulus, bending modulus, ultimate tensile strength, and fracture strain, are extracted from nanoindentation simulations and compared to the monolayer and homogeneous bilayer systems. We observed that the heterostructures, regardless of the stacking order, are mechanically more robust than the mono-and bi-layer MoS2, mainly due to the mechanical reinforcement provided by the graphene layer. The magnitudes of ultimate strength and fracture strain are similar for both the bi-and tri-layer heterostructures, but substantially larger than either the mono-and bi-layer MoS2. Our results demonstrate the potential of graphene-based heterostructures to improve the mechanical properties of TMDC materials.