High-performance pure blue phosphorescent OLED using a novel bis-heteroleptic iridium(iii) complex with fluorinated bipyridyl ligands

Abstract

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 (η_PL) of 78 ± 1%. A transient PL decay curve exhibited almost single-exponential decay (98%) with the phosphorescence lifetime (τ_p) of 1.51 μs at room temperature. A blue OLED with a structure of [ITO (130 nm)/TAPC (40 nm)/FK306 11–20 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.