Confined-state physics and signs of fermionization of moire excitons in WSe2/MoSe2 heterobilayers

We revisit and extend the standard bosonic interpretation of interlayer excitons (ILX) in the moire potential of twisted heterostructures of transition-metal dichalcogenides. In our experiments, we probe a high quality MoSe2/WSe2 van der Waals bilayer heterostructure via density-dependent photoluminescence spectroscopy and reveal strongly developed, unconventional spectral shifts of the emergent moire exciton resonances. The observation of saturating blueshifts of successive exciton resonances allow us to explain their physics in terms of a model utilizing fermionic saturable absorbers. This approach is strongly inspired by established quantum-dot models, which underlines the close analogy of ILX trapped in pockets of the moire potential, and quantum emitters with discrete eigenstates.