Optical identification of interlayer coupling of graphene/MoS2 van der Waals heterostructures

The interlayer coupling in van der Waals (vdW) heterostructures (vdWHs) is at the frontier of the fundamental research, underlying many optical behaviors. The graphene/MoS2 vdWHs provide an ideal platform to reveal the good interfacial coupling between graphene and MoS2 constituents. Here, three groups of graphene/MoS2 vdWHs were prepared by transferring 1-3 layers of graphene onto monolayer MoS2. The interlayer coupling within graphene/MoS2 vdWHs were characterized and analyzed by Raman spectroscopy, photoluminescence (PL) spectroscopy and optical contrast (OC) spectroscopy. The upshift of the A(1g) peak of MoS2 and the upshift of the D and 2D peaks of SLG show that the electrons move from MoS2 to graphene accompanied by the dielectric shielding effect on graphene. The weakened PL intensities and the slight red shift of A peak prove that the electrons move from MoS2 to graphene meanwhile the recombination of hole and electron pairs is blocked in vdWHs. Our results deepen the understanding of the interlayer coupling of graphene/MoS2 vdWHs and therefore provide guidelines for the practical design and application of optoelectronic devices based on graphene/MoS2 vdWHs.