New bipolar host materials based on isoquinoline and phenylcarbazole for red PhOLEDs

Three new bipolar host materials ( BPCzB , p -BPBCz and m -BPBCz ) which consist of carbazoles as electron donors (D) and an isoquinoline as an electron acceptor (A) were synthesized and characterized. They all exhibited excellent thermal stability and appropriate triplet energy levels ( E T ). Hence, red phosphorescent organic light-emitting diodes (PhOLEDs) based on the three hosts were fabricated. The device hosted by m -BPBCz with isoquinoline linked to the meta position of phenylcarbazole unit showed the best electroluminescent (EL) performance with a turn-on voltage of 3.4 V, a maximum brightness of 52840 cd/m 2 , a maximum current efficiency (η c,max ) of 29.60 cd/A, a maximum power efficiency (η p,max ) of 22.58 lm/W and an external quantum efficiency (EQE) of 17.2%, demonstrating its potential application as a host for practical applications in red PhOLEDs. Three new bipolar host materials ( BPCzB , p -BPBCz and m -BPBCz ) which consist of carbazoles as electron donors and an isoquinoline as an electron acceptor were synthesized and characterized. The red PhOLEDs hosted by m -BPBCz exhibited an EQE max of 17.2%. • Three bipolar hosts based on isoquinoline and phenylcarbazole were reported. • These materials show excellent thermal stability and appropriate HOMO/LUMO levels. • The red PhOLEDs hosted by m-BPBCz exhibit an EQEmax of 17.2%.