Phenanthridine based Ir(III) complex for blue phosphorescent organic light-emitting diodes with long-term operational stability

New Ir(III) compound with sky-blue phosphorescence has been synthesized by one-pot reaction of [Ir(COD)₂]BF₄ with 2,3-dimethylimidazo[1,2-f]phenanthridine. This complex has a facial(fac) geometry around iridium metal center. The ligand has been found to significantly interact with adjacent molecules through π-stacking interactions in solid state packing. The Ir(III) complex emits brightly sky blue phosphorescence with λ_max = 468 nm and quantum efficiencies of 0.23 in solution. Multi-layer electroluminescent devices using this complex as a dopant, and 1,3-bis(N-carbazolyl)benzene as the host/hole transporting layer, have been fabricated. The electroluminescence device at the doping level of 3–10 wt% has the excellent performance with external quantum efficiency of 15%–20% at the brightness of 10 cd/m²–1000 cd/m² and the maximum power efficiency of 35.9 lm/W.