In recent years, graphene-based van der Waals (vdW) heterostructures have come into prominence showcasing interesting charge transfer dynamics which is significant for optoelectronic applications. These novel structures are highly tunable depending on several factors such as the combination of the two-dimensional materials, the number of layers and band alignment exhibiting interfacial charge transfer dynamics. Here, we report on a novel graphene based 0D-2D vdW heterostructure between graphene and amine-functionalized graphene quantum dots (GQD) to investigate the interfacial charge transfer and doping possibilities. Using a combination ofab initiosimulations and Kelvin probe force microscopy (KPFM) measurements, we confirm that the incorporation of functional GQDs leads to a charge transfer induced p-type doping in graphene. A shift of the Dirac point by 0.05 eV with respect to the Fermi level (EF) in the graphene from the heterostructure was deduced from the calculated density of states. KPFM measurements revealed an increment in the surface potential of the GQD in the 0D-2D heterostructure by 29 mV with respect to graphene. Furthermore, we conducted power dependent Raman spectroscopy for both graphene and the heterostructure samples. An optical doping-induced gating effect resulted in a stiffening of theGband for electrons and holes in both samples (graphene and the heterostructure), suggesting a breakdown of the adiabatic Born-Oppenheimer approximation. Moreover, charge imbalance and renormalization of the electron-hole dispersion under the additional influence of the doped functional GQDs is pointing to an asymmetry in conduction and carrier mobility.

CEITEC Brno University of Technology Purkyňova 123 612 00 Brno Czech Republic

CEITEC Masaryk University Kamenice 62500 Brno Czech Republic

Department of Condensed Matter Physics Masaryk University Kotlářská 611 37 Brno Czech Republic

Department of Materials Science Montanuniversität Leoben Franz Josef Strasse 18 A 8700 Leoben Austria

Institute of Physics Montanuniversität Leoben Franz Josef Strasse 18 A 8700 Leoben Austria

Solar Cells and Photonics Research Laboratory School of Chemistry University of Hyderabad 500 46 Hyderabad Telangana India

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