Rich properties of two dimensional (2D) materials have been attracting great effort to exploration of novel 2D materials and quasi-2D systems. Van der Waals heterostructures are possible method to create quasi-2D systems, by layer-by-layer assemble of 2D atomical crystals. Free stacking with a variety of materials in different configurations are envisioned for van der Waals materials, owing to their weak interlayer binding energy, stable surface and lack of dangling bond. In this work, study of optical properties of van der Waals heterostructures of graphene and mica discovered the interfacial trap states induced trion splitting of MoS₂, illustrating the aspect of van der Waals heterostructures as quasi-2D systems. Besides, an exploration to possible synthesis of 2D polymers, a special...[ Read more ]

Rich properties of two dimensional (2D) materials have been attracting great effort to exploration of novel 2D materials and quasi-2D systems. Van der Waals heterostructures are possible method to create quasi-2D systems, by layer-by-layer assemble of 2D atomical crystals. Free stacking with a variety of materials in different configurations are envisioned for van der Waals materials, owing to their weak interlayer binding energy, stable surface and lack of dangling bond. In this work, study of optical properties of van der Waals heterostructures of graphene and mica discovered the interfacial trap states induced trion splitting of MoS₂, illustrating the aspect of van der Waals heterostructures as quasi-2D systems. Besides, an exploration to possible synthesis of 2D polymers, a special category of 2D materials, reveals another aspect of van der Waals heterostructures as a potential tool to fabricate 2D materials. The spreading of molecules as monolayer is found to be favored in the gap of van der Waals heterostructure of graphene and mica against a second layer. And the effects of graphene/mica heterostructure to dynamics of molecules at the interface are studied. Combining the features of dynamics of molecules trapped in van der Waals heterostructure and spreading at interface, reveals that the effects of forces of van der Waals heterostructures on molecules have great differences in layer number. This study demonstrates that van der Waals materials and their heterostructures open new ways to access to the atomical scale 2D materials and quasi-2D systems.