Simplified Bilayer White Phosphorescent Organic Light-Emitting Diodes

Abstract

We report on highly efficient blue, orange, and white phosphorescent organic light-emitting diodes consisting only two organic layers. Hole transporting 4, 4,′ 4″-tris (N-carbazolyl)triphenylamine (TcTa) and electron transporting 2-(diphenylphosphoryl) spirofluorene (SPPO1) are used as an emitting host for orange lightemitting bis(3-benzothiazol-2-yl-9-ethyl-9H-carbazolato) (acetoacetonate) iridium ((btc)2(acac)Ir) and blue lightemitting iridium(III)bis(4,6-difluorophenyl-pyridinato- N,C2′) picolinate (FIrpic) dopant, respectively. Combining these two orange and blue light-emitting layers, we successfully demonstrate highly efficient white PHOLEDs while maintaining Commission internationale de l'éclairage coordinates of (x = 0.373, y = 0.443). Accordingly, we achieve a maximum external quantum, current, and power efficiencies of 12.9%, 30.3 cd/A, and 30.0 lm/W without out-coupling enhancement.