Chiral Norbornene‐Integrated Ir (III) Complexes for Circularly Polarized Electroluminescence

A series of Ir (III) complexes with norbornene as the sterically hindered group, including one achiral Ir (III) complex and a pair of chiral Ir (III) complex isomers with chiral ligand, have been synthesized. Their photoluminescence wavelengths are about 510 nm, which belongs to green emission. These complexes exhibit phosphorescence lifetimes spanning 1.24 to 1.62 μs. The photoluminescent quantum yields (PLQYs) of the complexes are all more than 70%. Device performance evaluation shows that organic light‐emitting diodes (OLEDs) based on these complexes exhibit moderate electroluminescence performances, with the maximum external quantum efficiency (EQE max ) as high as 16.0%, and a relatively low efficiency roll‐off. Moreover, the devices exhibit clear CPEL activity, with dissymmetry factors ( g EL ) of opposite signs, reaching 3.2 × 10 −3 and −2.5 × 10 −3 , respectively. These experimental results demonstrate that the rigid chiral norbornene groups can not only reduce the concentration quenching of Ir (III) complexes, improve their electroluminescence efficiency, but also induce significant circularly polarized luminescence.