Abstract
Exciton dynamics in monolayer transition metal dichalcogenides (TMDCs) have garnered recent interest as a platform for optoelectronic devices and are often placed near metal interfaces or inside planar cavities. We compare the emission properties of excitons–which are fundamentally delocalized–in TMDCs near planar metal interfaces to point dipoles and explore their dependence on exciton center-of-mass momentum, transition dipole orientation, and temperature. In regimes where the momentum distribution can be characterized by Maxwell-Boltzmann statistics, the modified emission rates (normalized to free space) behave similarly to point dipoles due to the broad nature of wavevector components making up the exciton and point dipole emission. Conversely, the narrow momentum distribution of excitons at low temperatures results in significantly different emission behavior compared to point dipoles. At high phase space densities, excitons characterized by Bose-Einstein statistics exhibit modified emission rates that can be suppressed or enhanced relative to point dipoles by several orders of magnitude. These insights can help optimize optoelectronic devices that incorporate TMDCs near metal interfaces and can inform future studies of low temperature exciton radiative dynamics.
*DEC acknowledges support from the European Union's Horizon 2020 research and innovation programme, under European Research Council grant agreement No 101002107 (NEWSPIN); the Government of Spain (Europa Excelencia program EUR2020-112155, Severo Ochoa program CEX2019-000910-S, and MCIN Plan Nacional Grant PGC2018- 096844-B-I00); Generalitat de Catalunya through the CERCA program, AGAUR Project No. 2017-SGR-1334, Fundació Privada Cellex, and Fundació Mir-Puig. AB acknowledges support from the NSF Graduate Research Fellowship under grant no. DGE-1746045. GHC acknowledges support from the College Summer Undergraduate Research grant program and the Jeff Metcalf PME Fellowship at the University of Chicago.
