Efficient Low-Driving-Voltage Blue Phosphorescent Homojunction Organic Light-Emitting Devices

A blue phosphorescent p–i–n homojunction organic light-emitting device with a low driving voltage was demonstrated using 4,6-bis[3-(carbazol-9-yl)phenyl] pyrimidine (46DCzPPm) as the bipolar host material and iridium(III) bis[4,6-(difluorophenyl)pyridinato- N , C 2 '] picolinate as the blue triplet emitter. The device incorporated an n-doping electron-transport layer consisting of Cs 2 CO 3 -doped 46DCzPPm and a p-doping hole-transport layer consisting of MoO 3 -doped 46DCzPPm. A maximum external quantum efficiency of 10.2% and a power efficiency of 27.8 lm W -1 were obtained. At 100 cd m -2 , the efficiencies were 9.1% and 21.5 lm W -1 , and even at 1000 cd m -2 , the efficiencies remained at 7.0% and 12.8 lm W -1 , respectively, with an extremely low driving voltage of 3.9 V.