Heterostructures*

Van der Waals heterostructures allow for the exploration of interface physics without the constraint of lattice matching. In this study we examine proximity effects in a vdW heterostructure comprised of TiSe₂ and monolayer MoSe₂. Using temperature-dependent, spatially-resolved photoluminescence (PL) microscopy we discover a new MoSe₂ PL emission line at the TiSe₂-MoSe₂ interface. This PL line appears 30 meV above the MoSe₂ neutral exciton which excludes localized or trapped excitons as a viable explanation. Temperature-dependent measurements show a surprising correlation of the high energy PL line with the TiSe₂ CDW state, thus suggesting the CDW plays a central role in activating this previously unobserved exciton. We discuss possible CDW-based origins of this feature and outline future opportunities for using proximity effects in vdW heterostructures to engineer novel excitonic states.