Polarized Light‐Emitting Diodes Based on Anisotropic Excitons in Few‐Layer ReS₂

Abstract An on‐chip polarized light source is desirable in signal processing, optical communication, and display applications. Layered semiconductors with reduced in‐plane symmetry have inherent anisotropic excitons that are attractive candidates as polarized dipole emitters. Herein, the demonstration of polarized light‐emitting diode based on anisotropic excitons in few‐layer ReS₂, a 2D semiconductor with excitonic transition energy of 1.5–1.6 eV, is reported. The light‐emitting device is based on minority carrier (hole) injection into n‐type ReS₂ through a hexagonal boron nitride (hBN) tunnel barrier in a metal–insulator–semiconductor (MIS) van der Waals heterostack. Two distinct emission peaks from excitons are observed at near‐infrared wavelength regime from few‐layer ReS₂. The emissions exhibit a degree of polarization of 80% reflecting the nearly 1D nature of excitons in ReS₂.