Enhancing Quantum Dot LED Efficiency by Tuning Electron Mobility in the ZnO Electron Transport Layer

Abstract

Quantum-dot (QD) light-emitting diodes (QLEDs) are an important new class of optoelectronic device. Despite the ubiquity of ZnO as the electron-transport material in QLEDs, little is known about how its properties influence QLED performance. Here, it is demonstrated that the defect density and electron mobility of the ZnO nanoparticle electron-transport layer strongly affect QLED device efficiency and can be used to balance electron and hole injection into the QD layer. Films of ZnO nanoparticles exhibiting electron mobilities tuneable over an order of magnitude are made by annealing out defect states in suspensions of ZnO nanoparticles prior to deposition. By incorporating these ZnO films i..