Atomically thin 2D materials are good templates to grow organic semiconductor thin films with desirable features. However, the 2D materials typically exhibit surface roughness and spatial charge inhomogeneity due to nonuniform doping, which can affect the uniform assembly of organic thin films on the 2D materials. A hybrid template is presented for preparation of highly crystalline small‐molecule organic semiconductor thin film that is fabricated by transferring graphene onto a highly ordered self‐assembled monolayer. This hybrid graphene template has low surface roughness and spatially uniform doping, and it yields highly crystalline fullerene thin films with grain sizes >300 nm, which is the largest reported grain size for C60 thin films on 2D materials. A graphene/fullerene/pentacene phototransistor fabricated directly on the hybrid template has five times higher photoresponsivity than a phototransistor fabricated on a conventional graphene template supported by a SiO2 wafer.

This article describes a novel method for the direct synthesis of patterned graphene on transition-metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS 2 ) with chemical vapor deposition (CVD) that uses a UV/ozone-treated solid carbon source, 1,2,3,4-tetraphenylnaphthalene (TPN) as the graphene growth precursor. The UV/ozone treatment of the TPN film on the MoS 2 layer improves the interfacial adhesion between the TPN and MoS 2 layers. The surface-adhered TPN is directly converted to graphene on the MoS 2 layer, which results in a sharp interface between graphene and MoS 2 . The graphene/MoS 2 heterostructure with interfacial bonding yields excellent electrical and mechanical characteristics that facilitate charge injection by reducing contact resistance and improving bending stability. The excellent contact enhances the field-effect mobility of MoS 2 field-effect transistors to values up to three times higher than that of the devices using source-drain electrodes prepared with the conventionally transferred CVD-grown graphene. The proposed method for the direct synthesis of graphene on TMDs is expected to have wide applications in nanoelectronics based on 2D materials.

Polycyclic aromatic hydrocarbons (PAH) have been widely used as solid carbon sources for the synthesis of graphene at low temperatures. The inevitable formation of structural defects, however, has significantly limited the quality of the synthesized graphene. This article describes a low‐temperature chemical vapor deposition method that effectively mitigates defect formation in graphene by heterogeneous solid carbon sources containing a mixture of aromatic and aliphatic carbon on a Cu substrate. The addition of small amount of aliphatic carbon sources to the PAH significantly decreases the defect density of graphene synthesized at 400 ≤ T ≤ 600 °C by incorporating small aliphatic carbon fragments into defect sites. The carrier mobility of graphene grown using this heterogeneous solid carbon source is more than five times that of graphene synthesized using only PAH. Two mechanisms are also proposed by which vacancies can be generated during graphene growth using PAH sources on Cu, defect generation due to the disordered packing and the geometric limitation of PAH molecules. This low‐temperature method of synthesizing graphene reduces the degree of defect density using heterogeneous solid carbon sources promises to provide wide utility in electronics applications.

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