Color Stability and High Efficiency of White Phosphorescent Organic Light-Emitting Diodes with Suitable Position of Phosphorescent Red Emitter

Abstract

We have demonstrated high-efficiency phosphorescent white organic light-emitting diodes (PHWOLEDs) using iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C2] picolinate and iridium(III) bis[1-phenyl(quinolinato-N,C2')]acetylacetonate doped in N,N '-dicarbazolyl-3,5-benzene as a single-host system. As the position of the doped red emitter changed from near the anode to the cathode, the PHWOLED exhibited reduced exciton loss and greater color stability. The optimized PHWOLED exhibited a peak external quantum efficiency of 13.49%, a power efficiency of 20.59 lm/W, a current efficiency of 26.20 cd/A, and Commission Internationale de l'Eclairage coordinates of (0.37, 0.35). The red emitter near the cathode includes efficient triplet energy confinement in the emitting layers.