Enhanced Emission of Molybdenum Disulfide by Organic-Inorganic Hybrid Heterojunctions.

Due to their excellent stability and layer-dependent photoelectronic properties, transition metal dichalcogenides (TMDs) are one of the most extensively studied two-dimensional semiconductor materials in the postgraphene era. However, its low luminescence quantum yield limits its application in displays, lighting, and imaging. Here, a 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) layer was grown on the surface of chemical vapor deposition (CVD)-grown monolayer molybdenum disulfide (MoS) by vacuum evaporation, which increased the photoluminescence intensity of MoS by 15 times. The enhanced luminescence originates from the charge transfer from the conduction band of MoS to the lowest unoccupied molecular orbital (LUMO) of HATCN, which suppresses the emission of the negatively charged exciton (trion) while increasing the emission of the neutral exciton. Temperature-dependent fluorescence and Raman spectra demonstrate the feasibility of organic-inorganic hybrid heterojunctions for regulating excitons. This facile and practical organic-inorganic hybrid heterojunction can elevate TMD applications, such as light-emitting diodes.