LAUSR

Abstract High efficiency non-doped white organic light-emitting diodes (WOLEDs) have been realized by inserting an ultrathin yellow fluorescent emitter into a bilayer blue exciplex system. The white emission comes from the incomplete energy transfer from the blue exciplex to the yellow fluorescent emitter. By tuning the location of the ultrathin fluorescent emitter layer in the device, excitons directly formed in the yellow fluorophore can be neglected and the Dexter energy transfer from triplet state of exciplex to yellow fluorophore is also suppressed, contributing to the high efficiency. The WOLED achieves a maximum current efficiency of 27.2 cd/A, with Commission Internationale de I'Eclairage (CIE) coordinates of (0.35 ± 0.02, 0.38 ± 0.02).