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 condensation^1-3 to analogue Hamiltonian simulators^4,5 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.