Highly Efficient Blue Single-Emitting Layer Phosphorescent Organic Light-Emitting Diodes with a Low Driving Voltage

A high performance blue electroluminescent (EL) device was prepared by employing iridium(III)bis[4,6-difluorophenyl)-pyridinato-N,C2']picolinate (FIrpic) as a phosphorescence guest material with energy level matched host materials. The doping concentration of the blue-emitting material and the thickness of the host material were strictly optimized, current density-brightness-voltage (J-B-V) characteristic curve and normalized EL spectrum of the device were analyzed and studied. Comparison of three devices with different structures prepared by using two host materials, the experimental results demonstrated that the mCP-based single light-emitting layer devices exhibit lower operating voltage, as well as higher efficiency and brightness. Finally, the device with a doping concentration of 16 wt% and the thickness of mCP is 14 nm achieves the maximum current efficiency, power efficiency of up to 43. 0Scd/A and 50.13 1m/W, respectively. Even at the high brightness of 1000 cd/m
²
, the operating voltage is only 4.4 V obtained.