Electrically Tunable Exciton and Telecom-Band Light-Emitting Diodes in Few-Layer Phosphorene

Two-dimensional (2D) semiconductors with direct band gaps offer opportunities for constructing ultrathin and compactly integrated light-emitting diodes (LEDs). Current LEDs based on 2D semiconductors mostly work in the visible light spectrum rather than the near-infrared telecommunication band, hindering their incorporation into established applications such as optical computing and communication. In this study, we report on the LED from the bilayer and trilayer phosphorene in the near-infrared regime leveraging the direct bandgap nature of black phosphorus (BP). The layer-number-sensitive electrical field regulation characteristics of bright excitons in bilayer and trilayer phosphorene were revealed. Moreover, the dominating exciton types and emission wavelengths were demonstrated to be dynamically regulated from a single trilayer phosphorene-based LED near 1500 nm by judiciously controlling the electric field and carrier injection conditions. The findings suggest the potential application of 2D semiconductors in miniaturized light source devices operating in the near-infrared telecommunication band.