High-performance pure blue phosphorescent OLED using a novel bis-heteroleptic iridium(III) complex with fluorinated bipyridyl ligands
A novel pure blue phosphorescent emitter FK306 with fluorinated bipyridyl ligands was developed. The I-p level was determined to be 6.3 eV by photoelectron yield spectroscopy (PYS) in the solid state. The photophysical properties of a FK306/mCP film were evaluated. An 11 wt% doped film showed a peak photoluminescence at 454 nm and a high photoluminescent quantum yield (eta(PL)) of 78 +/- 1%. A transient PL decay curve exhibited almost single-exponential decay (98%) with the phosphorescence lifetime (tau(p)) of 1.51 mu s at room temperature. A blue OLED with a structure of [ITO (130 nm)/TAPC (40 nm)/FK30611-20 wt% doped mCP (10 nm)/B3PyPB (50 nm)/LiF (0.5 nm)/Al (100 nm)] was fabricated and evaluated. A high power efficiency of over 30 lm W-1 and an external quantum efficiency of over 17% were observed. The CIE chromaticity diagram (x, y) was evaluated to be (0.16, 0.25), clearly indicating blue emission. These are the first decent performances using a blue emitter with bipyridyl ligands so far.