  The vertical stacking of two-dimensional materials into heterostructures
gives rise to a plethora of intriguing optoelectronic properties and presents
an unprecedented potential for technological development. While much progress
has been made combining different monolayers of transition metal
dichalgonenides (TMDs), little is known about TMD-based heterostructures
including organic layers of molecules. Here, we present a joint
theory-experiment study on a TMD/tetracene heterostructure demonstrating clear
signatures of spatially separated interlayer excitons in low temperature
photoluminescence spectra. Here, the Coulomb-bound electrons and holes are
localized either in the TMD or in the molecule layer, respectively. In
particular, we reveal both in theory and experiment signatures of the entire
intra- and interlayer exciton landscape in the photoluminescence spectra. In
particular, we find both in theory and experiment a pronounced transfer of
intensity from the intralayer TMD exciton to a series of energetically lower
interlayer excitons with decreasing temperature. In addition, we find
signatures phonon-sidebands stemming from these interlayer exciton states. Our
findings shed light on the microscopic nature of interlayer excitons in
TMD/molecule heterostructures and could have important implications for
technological applications of these materials.
