A polaron-polariton light-emitting diode

Quasiparticles arising from the interaction between mobile impurities and quantum many-body environments—known as polarons—play a pivotal role in shaping the optical and electronic properties of low-dimensional systems. Leveraging recent advances in their optical control, we realize a many-body light-emitting diode (LED) that utilizes polaron–polaritons, hybrid light–matter quasiparticles formed by strongly coupled polarons and cavity photons, as the active emission species. Our device, based on a monolayer transition metal dichalcogenides (TMDCs) embedded in a planar microcavity, achieves an external quantum efficiency of 1.1%, representing a tenfold improvement over monolayer WS2-based exciton-polariton LEDs. This demonstration establishes a versatile platform for inversionless laser technology and for polariton-based quantum optoelectronics, while offering new insights into radiative many-body physics in two-dimensional semiconductors.