A series of novel non-conjugated functionalized benzoimidazole-based dendrimers containing peripheral benzyl ether type dendrons have been synthesized and characterized. These compounds undergo cyclometalation with iridium trichloride to form iridium(III) complexes. The emission wavelengths of these dendrimers are in the range from 510 to 530 nm, and the photoluminescence quantum yields (PLQYs) in the range from 0.45 to 0.80. Dendrimers (Gn)2Ir(acac) and (Gn)3Ir exhibit a reversible one-electron oxidation wave at ∼0.55 V and ∼0.37 V (vs. Ag/AgNO3), respectively. With a device configuration of indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid)/4,4′-bis(N-carbarzolyl)biphenyl:(G2)3Ir 20 wt% dopant/1,3,5-tris(2-N-phenyl-benzoimidazolyl)benzene/LiF/Al has a maximum external quantum efficiency (EQE) of 17.6% and a maximum current efficiency of 61.5 cd/A.
- Iridium complexes
- Light-emitting diodes