Balancing the white emission of OLEDs by a tandem structure with an effective charge generation layer

In this paper, we performed the design on the structure of white organic light-emitting diodes (WOLEDs). Use of a tandem structure based on lithium fluoride (LiF)-doped 4,7-diphenyl-1,10-phenanthroline (Bphen:LiF)/Al/molybdenum trioxide (MoO3) as an effective intermediate charge generation layer (CGL), which makes up for the deficiency of the color coordinates, yields relatively broadband white emission. Although single WOLEDs using 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin (BCP) as hole blocking layer produced white light emission with Commission Internationale d’Eclairage (CIE) coordinates of (0.28, 0.39) at 10 mA/cm2, the optimized tandem WOLEDs demonstrated that the color coordinates were improved to (0.41, 0.42). The maximum efficiency was enhanced from 2.73 cd/A to 18.6 cd/A as well.