Room‐Temperature Polarized Light‐Emitting Diode‐Based on a 2D Monolayer Semiconductor

Transition metal dichalcogenide (TMD)‐based 2D monolayer semiconductors, with the direct bandgap and the large exciton binding energy, are widely studied to develop miniaturized optoelectronic devices, e.g., nanoscale light‐emitting diodes (LEDs). However, in terms of polarization control, it is still quite challenging to realize polarized electroluminescence (EL) from TMD monolayers, especially at room temperature. Here, by using Ag nanowire top electrode, polarized LEDs are demonstrated based on 2D monolayer semiconductors (WSe2, MoSe2, and WS2) at room temperature with a degree of polarization (DoP) ranging from 50% to 63%. The highly anisotropic EL emission comes from the 2D/Ag interface via the electron/hole injection and recombination process, where the EL emission is also enhanced by the polarization‐dependent plasmonic resonance of the Ag nanowire. These findings introduce new insights into the design of polarized 2D LED devices at room temperature and may promote the development of miniaturized 2D optoelectronic devices. Polarized light‐emitting diodes (LEDs) based on 2D monolayer semiconductors are demonstrated at room temperature by using single Ag nanowires as both the electrical contact and the plasmonic resonant nanocavity. The polarized 2D LEDs show pronounced linear polarization dependency with a degree of polarization as high as 63% and work with multiple types of monolayers, e.g., WSe2, MoSe2, and WS2.