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 (MoS₂) by vacuum evaporation, which increased the photoluminescence intensity of MoS₂ by 15 times. The enhanced luminescence originates from the charge transfer from the conduction band of MoS₂ 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.