Heteroleptic cyclometalated iridium(III) complexes featuring lepidine-based ligands and acetyl acetone auxiliary ligand are synthesized. Multiple lowest energy absorption bands are observed for these complexes indicating substantial mixing of the singlet and triplet levels. All the complexes emit orange or red color in dichloromethane solutions with lifetimes in the range 1.6-3.7 micros. The emission in the complexes probably originates from the (3)MLCT state. The complexes are applied as emitting guests in LED devices of the structure ITO/HTL(BPAPF or NPB)/6% Ir in CBP/BCP/Alq(3)/LiF/Al. They exhibit excellent device characteristics with an orange to red EL profile.
A new series of lepidine-containing-ligand-based cyclometalated platinum(II) complexes 1-7 with general formula [Pt(L)acac] (L = lepidine-based ligand, acac = acetylacetonate) have been synthesized. The complexes have been characterized using spectral and electrochemical techniques. The single-crystal X-ray structures of complexes 2 and 5 have been successfully determined. The effects of substituents on the electronic features and redox potentials of the cyclometalated phenyl ring of the complexes are discussed. Complexes 1-7 are highly phosphorescent in fluid as well as in solid state, covering a rather broad spectral range from yellow to saturated red. These complexes were successfully used as a dopant material to fabricate the electroluminescent device, ITO/NPB (40 nm)/ CBP-doped Pt complex (5 wt %) (20 nm)/BCP (10 nm)/Alq 3 (20 nm)/LiF (1 nm)/Al (150 nm), which exhibits very promising performance. The device doped with 5 wt % 3 produced a maximum external quantum efficiency of 15.2% with a maximum brightness of 26847 cd m -2 and corresponds to a luminance efficiency of 29.83 cd A -1 .
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