Triphenylamine-functionalized iridium(III) complexes for near-infrared phosphorescent organic light emitting diodes

With the aim of enhancing the efficiency of near infrared (NIR) organic light-emitting devices (OLEDs), two new triphenylamine-functionalized NIR iridium(III) complexes by covalently attaching the functional moieties (tBu and F) complexes (tBuTPA-BTz-Iq)(2)Irpic and (FTPA-BTz-Iq)(2)Irpic were designed and synthesized (TPA = triphenylamine; BTz = benzotriazole; Iq = isoquinoline). It was found that compared to their parent iridium complex (TPA-BTz-Iq)(2)Irpic, the addition of either butyl or fluorine groups into the ligand play an important role in improving the optophysical and electroluminescent characteristics. In solution-processed phosphorescent OLEDs, the (tBuTPA-BTz-Iq)(2)Irpic-based devices achieved a maximum external quantum efficiency (EQE(max)) of 0.66% at 716 nm, while the (FTPA-BTz-Iq)(2)Irpic-based devices achieved an EQE(max) of 0.48% at 710 nm. The EQE(max) level is 2.28 or 1.65 times higher than that in the (TPA-BTz-Iq)(2)Irpic-based devices (0.29% at 712 nm), respectively.