Achieving Balanced Charge Injection of Blue Quantum Dot Light-Emitting Diodes through Transport Layer Doping Strategies.

For blue quantum dot (QD) light-emitting diodes (QLEDs), the imbalance of charges transport and injection severely affects their efficiency and lifetime. A better charge balance can be realized by improving hole injection while suppressing redundant electrons. Introducing dopants into charge transport layers (CTLs) is an effective and simple strategy to modulate the charge injection barrier and mobility. In this work, optoelectronic simulation is performed to investigate the change in physical process within the devices upon CTL doping. The results confirm that the charge distribution in the QD layer is more balanced and the recombination rate is greatly improved. Under the guidance of theoretical simulation, high-performance blue QLEDs were achieved by fine-tuning the charge balance through CTL doping. The luminance and external quantum efficiency have been dramatically increased from 18 679 to 34 874 cd/m2 and from 4.7 to 10.7%, respectively. The operation lifetime is also improved ∼3.5 times due to the more balanced charge injection.