Highly Efficient Light-Emitting Diodes based on Self-Assembled Colloidal Quantum Wells.

Nanocrystal-based light-emitting diodes (Nc-LEDs) have immense potential for next-generation high-definition displays and lighting applications. They offer numerous advantages, such as low cost, high luminous efficiency, narrow emission, and long lifetime. However, the external quantum efficiency (EQE) of Nc-LEDs, typically employing isotropic nanocrystals, has been limited by the out-coupling factor. Here we demonstrate efficient, bright, and long lifetime red Nc-LEDs based on anisotropic nanocrystals of colloidal quantum wells (CQWs). Through modification of the substrate's surface properties and control of the interactions among CQWs, we successfully spin-coated a self-assembled layer with an exceptionally high distribution of in-plane transitions dipole moment (TDM) of 95%, resulting in an out-coupling factor of 37%. Our devices exhibit a remarkable peak external quantum efficiency (EQE) of 26.9%, accompanied by a maximum brightness of 55,754 cd m -2 and a long operational lifetime (T 95 @100 cd m -2 ) over 15,000 h. These achievements represent a significant advancement compared to previous studies on Nc-LEDs incorporating anisotropic nanocrystals. We expect our work to provide a general self-assembly strategy for enhancing the light extraction efficiency of Nc-LEDs based on anisotropic nanocrystals. This article is protected by copyright. All rights reserved.