Highly efficient green and white fluorescent organic electroluminescent devices with co-doped electron transport material as both supplementary host and blue emitter

Abstract

An alternative approach was exploited to achieve high performance fluorescent organic light-emitting diodes (OLEDs) by co-doping traditional electron transport material into hole dominant light-emitting layer as supplementary host and blue emitter. Experimental results demonstrated that in this device structure, the co-doping of supplementary host was beneficial in broadening recombination zone, improving carriers trapping and facilitating the balance of holes and electrons, due to its well matched energy levels and high electron mobility. Based on this device design strategy, the optimized green electroluminescent (EL) device obtained the maximum brightness and external quantum efficiency up to 21176 cd/m2 and 5.4%, respectively, which are higher than those of reference devices. In addition, bright white OLED with the maximum brightness, current efficiency and external quantum efficiency up to 17207 cd/m2, 10.47 cd/A and 4.4%, respectively, was realized by modulating the doping concentrations of blue-emitting electron transport material and orange-emitting material. Thus, our investigation provides a chance to construct high performance white OLEDs with simplified device structure.