Enhanced Carrier Mobility by Doping NaCl in a Hole-Transport Layer for Electroluminescent Quantum Dots Light-Emitting Diodes

A feasible method to improve the charge balance of electroluminescent (EL) quantum dot (QD) light-emitting diodes (QLEDs) fabricated in the atmosphere is first demonstrated. Sodium chloride (NaCl) is introduced to poly(vinylcarbazole) (PVK), a conventional hole-transport layer (HTL), which exhibits enhanced hole mobility. According to the electronic current mapping of the NaCl-doped PVK film, it is proven that NaCl can locally increase the current density of PVK films. The photoluminescence quantum yield (PLQY) of QDs on a PVK:NaCl film also increases by 25.1% (∼11.3%) compared with those coated on pure PVK film. The introduction of NaCl to atmosphere-process-based EL QLEDs significantly increases the current efficiency by ∼53% and elongates the operation stability by ∼275%, compared with that with pure PVK, which is ascribed to improved hole mobility, leading to more efficient carrier recombination in the NaCl-doped QLED devices.