Improving Charge Injection via a Blade-Coating Molybdenum Oxide Layer: Toward High-Performance Large-Area Quantum-Dot Light-Emitting Diodes

A solution-processed molybdenum oxide (MoOx) as the hole injection layer (HIL) by doctor-blade coating was developed to improve the efficiency and lifetime of red-emitting quantum-dot light-emitting diodes (QD-LEDs). It has been demonstrated that by adding isopropyl alcohol into the MoOx precursor during the doctor-blade coating process, the morphology, composition, and the surface electronic structure of the MoOx HIL could be tailored. A high-quality MoOx film with optimized charge injection was obtained, based on which all-solution-processed highly efficient red-emitting QD-LEDs were realized by using a low-cost doctor-blade coating technique under ambient conditions. The red QD-LEDs exhibited the maximum current efficiency and external quantum efficiency of 16 cd/A and 15.1%, respectively. Moreover, the lifetime of red devices initializing at 100 cd/m2 was 3236 h under ambient conditions, which is about twice as long as those with a conventional poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) H...