Materials science

Optoelectronics

Physics

Graphene

Quantum mechanics

Photoluminescence

Nanotechnology

Semiconductor

Spectral line

Nature Nanotechnology

Atomically thin semiconductors made from transition metal dichalcogenides (TMDs) are model systems for investigations of strong light–matter interactions and applications in nanophotonics, optoelectronics and valleytronics. However, the photoluminescence spectra of TMD monolayers display a large number of features that are particularly challenging to decipher. On a practical level, monochromatic TMD-based emitters would be beneficial for low-dimensional devices, but this challenge is yet to be resolved. Here, we show that graphene, directly stacked onto TMD monolayers, enables single and narrow-line photoluminescence arising solely from TMD neutral excitons. This filtering effect stems from complete neutralization of the TMD by graphene, combined with selective non-radiative transfer of long-lived excitonic species to graphene. Our approach is applied to four tungsten- and molybdenum-based TMDs and establishes TMD/graphene heterostructures as a unique set of optoelectronic building blocks that are suitable fo...

Filtering the photoluminescence spectra of atomically thin semiconductors with graphene