Efficient Short‐Wave Infrared Light‐Emitting Diodes Based on Heavy‐Metal‐Free Quantum Dots

Abstract Short‐wave infrared (SWIR) light emission is important for a diverse range of modern applications, such as eye‐safe depth sensing, light detection and ranging (LiDAR), facial recognition, eye tracking, optical communication, and health‐monitoring technologies. However, there are a very limited number of known semiconductors that can emit efficiently in the SWIR spectral range. Presently, SWIR light‐emitting diodes (LEDs) based on colloidal quantum dots (CQD) are dominated by lead chalcogenide systems, despite the presence of heavy metal and modest efficiencies. Here, a highly efficient SWIR LED based on heavy‐metal‐free indium arsenide (InAs) core–shell CQDs is presented. In the LED design, the implementation of an otherwise hole‐transporting poly(vinylcarbazole) (PVK) layer on the electron‐injecting side of the device stack leads to a surprising enhancement in device performance, giving remarkably high external quantum efficiencies (EQEs) of 13.3% at 1006 nm. Single‐carrier device and optical investigations reveal the origins of enhancement to be the electronic decoupling of the CQD layer with the electron‐injecting zinc oxide (ZnO) layer, which mitigates luminescence quenching and improves charge balance. This work marks one of the highest efficiencies reported for heavy‐metal‐free solution‐processed LEDs in the SWIR spectral region, and can find significant applications in emerging consumer electronic technologies.