Mechanical properties of bilayer WSand Graphene-WSHybrid composites by molecular dynamics simulations.

In the present work, by using molecular dynamics (MD) simulations, we investigate the mechanical properties of different nanostructures that may be core elements in next generation flexible/wearable photovoltaic devices, namely double layer WSnanosheets (DLNS), graphene/WS(layer) composites and graphene/WSnanotube (NT) composites. Our results reveal that the mechanical properties of DLNS deteriorate when compared to those of monolayer WS. Owing to graphene's reinforcement action, the mechanical properties of graphene/WS(layer) composite with both layers deformed are superior than those of WS, even though inferior than those of bare graphene. If stress is applied only to the graphene layer, the graphene/WScomposite retains the most of the strength and toughness of monolayer graphene, decreasing the fracture strength and Young's modulus by only 9.7% and 16.3%, respectively. Similarly, in the case of the graphene/WSNT composite the mechanical strength and toughness experience a reduction compared to monolayer graphene, specifically by 15% and 53% for fracture strength and Young's modulus, respectively. Considering the market's keen interest in nanomaterials, particularly van der Waals (vdW) ones, for flexible and wearable photovoltaic devices, the findings presented here will significantly enhance the effective utilization of vdW composites.