Highly Polarized Narrow Linewidth Near-Infrared Emission from InSe-Based Light-Emitting Diodes.

Near-infrared (NIR) light-emitting diodes (LEDs) operating beyond 900 nm are critical for biomedical imaging and optical communications. However, achieving spectrally narrow emission with controlled polarization remains challenging. This work demonstrates electrically pumped NIR LEDs exploiting P-band emission in two-dimensional layered indium selenide (InSe). The P-band emission stems from exciton-exciton scattering, which is further enhanced by the formation of propagating exciton polaritons in the InSe crystal. Using a vertically stacked Au/InSe/Ag nanowire heterostructure, we achieved edge-localized P-band emission featuring narrow linewidth (Δλ < 20 nm), quadratic power dependence, and high linear polarization (∼80%). The P-band LED could operate continuously for more than 10 h with 96.3% intensity retention. Our approach establishes a new pathway for developing advanced on-chip NIR light sources, holding significant potential for applications in deep-tissue bioimaging and optical communication systems.