#van der waals

Beyond van der Waals: The next generation of covalent 2D-2D heterostructures

A team of scientists have “velcroed” 2D structures of MoS₂ and graphene using a covalent connection for the first time. The 2D-2D structures were used to build robust field effect transistors with controlled electronic communication, interface chemical nature and interlayer distance.

The most widespread method for the synthesis of 2D-2D heterostructures is the direct growth of materials on top of each other. 2D structures are atomically thin layered materials that can be stacked to build functional heterostructures. In such structures built by atomic deposition, 2D layers are weakly bonded by van der Waals interactions and can be taken apart in some solvents or thermal processes. The lack of control over the interface of the two materials in terms of electronic communication, chemical nature or interlayer distance thus impedes the construction of robust multi-purpose devices.

A team of researchers at Universidad Autónoma de Madrid and IMDEA Nanociencia (Spain) have connected covalently for the first time layers of 2D materials: MoS₂andgraphene. The team has used the tools of synthetic chemistry to “sew” several flakes of MoS₂ to single-layer graphene devices, using a bifunctional molecule with two anchor points. The results, published now in Nature Chemistry, show that the final electronic properties of the heterostructure are dominated by the molecular interface.

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