An Ultrahigh Efficiency Excitonic Micro-LED

High efficiency micro-LEDs, with lateral dimensions as small as one micrometer, are desired for next-generation displays, virtual/augmented reality, and ultrahigh-speed optical interconnects. The efficiency of quantum well LEDs, however, is reduced to negligibly small values when scaled to such small dimensions. Here, we show such a fundamental challenge can be overcome by developing nanowire excitonic LEDs. Harnessing the large exciton oscillator strength of quantum-confined nanostructures, we demonstrate a submicron scale green-emitting LED having an external quantum efficiency and wall-plug efficiency of 25.2% and 20.7%, respectively, the highest values reported for any LEDs of this size to our knowledge. We established critical factors for achieving excitonic micro-LEDs, including the epitaxy of nanostructures to achieve strain relaxation, the utilization of semipolar planes to minimize polarization effects, and the formation of nanoscale quantum-confinement to enhance electron-hole wave function overlap. This work provides a viable path to break the efficiency bottleneck of nanoscale optoelectronics.

Automated summary

By developing nanowire excitonic LEDs, the challenge of reduced efficiency in quantum well LEDs at small dimensions can be overcome. A submicron scale green-emitting LED with an external quantum efficiency of 25.2% and a wall-plug efficiency of 20.7% was achieved, the highest values reported for LEDs of this size to our knowledge. Critical factors for achieving excitonic micro-LEDs were identified, including epitaxy of nanostructures for strain relaxation, utilization of semipolar planes to minimize polarization effects, and formation of nanoscale quantum confinement to enhance electron-hole wave function overlap. This work provides a viable path to break the efficiency bottleneck of nanoscale optoelectronics.