Interlayer coupling and optoelectronic properties of ultrathin two-dimensional heterostructures based on graphene, MoS₂ and WS₂

Unique optoelectronic properties and interlayer coupling are observed in the artificial two-dimensional (2D) heterostructures based on graphene, MoS₂ and WS₂ monolayers. In the graphene-WS₂ heterostructures, substantial photoluminescence (PL) quenching and significant stiffening phonon modes emerge due to strong interlayer coupling. Such hybrid systems also exhibit gate-tunable current rectification behavior with a maximum rectification ratio of 10³. In addition, the ambipolar properties originating from their constituents and enhanced photo-switching properties with a maximum on/off ratio of 10³ were also observed. The MoS₂-WS₂ heterostructures exhibit light emission quenching of WS₂ while unchanged emission of MoS₂. Such a phenomenon is due to the weak interlayer coupling and inefficient charge transfer process. The enhanced optoelectronic performances suggest that the ultrathin 2D heterostructures have great potential in the future architectural design of novel optoelectronic devices.