Intercalation and hybrid heterostructure integration of two-dimensional atomic crystals with functional organic semiconductor molecules

Van der Waals (vdW) integration affords semiconductor heterostructures without constrains of lattice matching and opens up a new realm of functional devices by design. A particularly interesting approach is the electrochemical intercalation of two-dimensional (2D) atomic crystal and formation of superlattices, which can provide scalable production of novel vdW heterostructures. However, this approach has been limited to the use of organic cations with non-functional aliphatic chains, therefore failed to take the advantage of the vast potentials in molecular functionalities (electronic, photonic, magnetic, etc.). Here we report the integration of 2D crystal (MoS₂, WS₂, highly oriented pyrolytic graphite (HOPG), WSe₂ as model systems) with electrochemically inert organic molecules that possess semiconducting characteristics (including perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA), pentacene and fullerene), through on-chip electrochemical intercalation. An unprecedented long-range spatial feature of intercalation has been achieved, which allowed facile assembly of a vertical MoS₂-PTCDA-Si junction. The intercalated heterostructure shows significant modulation of the lateral transport, and leads to a molecular tunneling characteristic at the vertical direction. The general intercalation of charge neutral and functional molecules defines a versatile platform of inorganic/organic hybrid vdW heterostructures with significantly extended molecular functional building blocks, holding great promise in future design of nano/quantum devices. [Figure not available: see fulltext.]