Interlayer Energy Transfer and Photoluminescence Quenching in MoSe2/Graphene van der Waals Heterostructures for Optoelectronic Devices

van der Waals (vdW) heterostructures composed of multiple vertical stacks of two-dimensional materials exhibit unique optoelectronic properties compared with their single constituent counterparts. The interlayer coupling between adjacent layers directly affects the transfer of excitons and charges, thereby governing the device performance. Herein, we report that the interlayer energy transfer occurring in a transition-metal dichalcogenide/graphene vdW heterostructure strongly depends on the interlayer distance and modulates photocurrent generation. MoSe2/graphene and MoSe2/hexagonal boron nitride (h-BN)/graphene heterostructures comprising chemical-vapor-deposition-grown layers show different degrees of photoluminescence (PL) quenching of MoSe2 with respect to the number of layers and the types of adjacent layers. Comparisons of the Raman and PL spectra revealed that the h-BN interlayer can modulate the long-range exciton energy transfer from MoSe2 to graphene, as corroborated by the photocurrent measurements from the photoconductor devices. These results underscore the effect of modulating the interlayer coupling in vdW heterostructures on the fabrication and control of optoelectronic devices.