Featuring a high bandgap of 3.1 eV and a small ΔEST of 0.06 eV, DIC-TRZ is commonly used as bipolar TADF host for highly efficient OLED devices. It has a structure of an electron-donating indolo[2,3-a]carbazole (23aIC) unit and an electron-accepting diphenyl-1,3,5-triazine (TRZ) unit. A green phosphorescent OLED based on T3PyTRZ as the electron transport and DIC-TRZ as the host simultaneously achieves a low turn-on voltage at 1 cd/m2 of 2.18 V, a high EQE of over 24%, a high power efficiency of over 115 lm/W. Even at a high brightness of 1000 cd/m2, the driving voltage was only 2.88 V.

A three-component light-emitting layer consisting of DIC-TRZ as the host, Ir(piq)3 as the phosphorescent assist dopant, and Pt(tpbp) as the phosphorescent emitter simultaneously demonstrates high efficiency and long lifetime in the NIR. Efficient energy transfer between the two phosphorescent materials can be realized with 1 wt% doping ratio of the NIR emitter to significantly enhance the external quantum efficiency reaching 10.5% with an emission peak at 769 nm. The device shows a low drive voltage and a long operational lifetime, with a luminance decay of less than 11% from the initial value after 4800 h under accelerated conditions of 100 mA cm-2.

The hyperfluorescence OLED based on phosphorescent emitter Ir(ppy)3, DIC-TRZ as the host, and