Molecular dipole interfacial engineering for high-performance quantum-dot light-emitting diodes

Abstract

Balancing carrier injection via improving hole injection capability plays a key role for high-performance quantum dot light-emitting diodes (QLEDs). Herein, a self-assembled monolayer of carbazole-based derivatives is utilized to construct a dipole functional layer at the interface between the hole transport layer (HTL) and quantum dots (QDs) to facilitate hole injection. Additionally, rational interface engineering significantly reduces the trap-state density because of the highly ordered molecular arrangement. The resultant QLEDs present promising maximum external quantum efficiencies (EQEs) of 25.03%, which are remarkably higher than that of the control ones (20.58%). The optimized device produces outstanding stability and achieves a long operation lifetime (T95 lifetime at 1000 cd m−2, 14695 h) in the air. This simple strategy presents how to raise hole injection by constructing a dipole interface and optimizing molecular arrangement to improve the performance of QLED.