Control over the optical properties of atomically thin two-dimensional (2D) layers, including those of transition metal dichalcogenides (TMDs), is needed for future optoelectronic applications. Here, the near-field coupling between TMDs and graphene/graphite is used to engineer the exciton line shape and charge state. Fano-like asymmetric spectral features are produced in WS2, MoSe2, and WSe2 van der Waals heterostructures combined with graphene, graphite, or jointly with hexagonal boron nitride (h-BN) as supporting or encapsulating layers. Furthermore, trion emission is suppressed in h-BN encapsulated WSe2/graphene with a neutral exciton red shift (44 meV) and binding energy reduction (30 meV). The response of these systems to electron beam and light probes is well-described in terms of 2D optical conductivities of the involved materials. Beyond fundamental insights into the interaction of TMD excitons with structured environments, this study opens an unexplored avenue toward shaping the spectral profile of narrow optical modes for application in nanophotonic devices.

Central European Institute of Technology Brno University of Technology Brno 612 00 Czech Republic

College of Materials Science and Optoelectronic Technology University of Chinese Academy of Sciences Beijing 100083 China

Department of Materials Imperial College London London SW7 2AZ U K

Department of Physics Bar Ilan University Ramat Gan 5290002 Israel

Graduate Institute of Applied Science and Technology National Taiwan University of Science and Technology Taipei 106 Taiwan

ICFO Institut de Ciències Fotòniques The Barcelona Institute of Science and Technology 08860 Castelldefels Spain

ICREA Institució Catalana de Recerca i Estudis Avançats Passeig Lluís Companys 23 08010 Barcelona Spain

Indian Institute of Science Education and Research Dr Homi Bhabha Road 411008 Pune India

Institute of Physical Engineering Brno University of Technology Brno 616 69 Czech Republic

Institute of Physics and Center for Nanotechnology University of Münster 48149 Münster Germany

Research Center for Electronic and Optical Materials National Institute for Materials Science 1 1 Namiki Tsukuba 305 0044 Japan

Research Center for Materials Nanoarchitectonics National Institute for Materials Science 1 1 Namiki Tsukuba 305 0044 Japan

State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China

Université Côte d'Azur CNRS CRHEA 06560 Valbonne Sophia Antipolis France

Université Paris Saclay CNRS Institut des Sciences Moléculaires d'Orsay 91405 Orsay France

Université Paris Saclay CNRS Laboratoire de Physique des Solides 91405 Orsay France

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