A room-temperature polariton light-emitting diode based on monolayer WS2.

Exciton polaritons that arise through the strong coupling of excitons and cavity photons are used to demonstrate a wide array of fundamental phenomena and potential applications that range from Bose-Einstein-like condensation1-3 to analogue Hamiltonian simulators4,5 and chip-scale interferometers6. Recently, the two-dimensional (2D) transition metal dichalcogenides (TMDs), because of their large exciton binding energies, oscillator strength and valley degree of freedom, have emerged as a very attractive platform to realize exciton polaritons at elevated temperatures7. Achieving the electrical injection of polaritons is attractive both as a precursor to realizing electrically driven polariton lasers as well as for high speed light-emitting diodes (LEDs) for communication systems. Here, we demonstrate an electrically driven polariton LED that operates at room temperature using monolayer tungsten disulfide (WS2) as the emissive material. The extracted external quantum efficiency is ~0.1% and is comparable to recent demonstrations of bulk organic8 and carbon nanotube-based polariton electroluminescence (EL) devices9. The possibility to realize electrically driven polariton LEDs in atomically thin semiconductors at room temperature presents a promising step towards achieving an inversionless electrically driven laser in these systems as well as for ultrafast microcavity LEDs using van der Waals (vdW) materials.