New structure host material for phosphorescent OLED devices

New carbazole and quinoxaline based low molar mass bipolar derivative was synthesized, characterized, and tested as host derivative in phosphorescent organic light emitting diodes (OLEDs). The material could form homogeneous amorphous materials (layers) with very high glass transition temperature of 136 °C and also with very high initial thermal decomposition temperature of about 387 °C. The electron photoemission spectra of the layers of the synthesized compound showed ionization potentials of about 5.85 eV. The compound was tested as host material for green Ir(ppy)3 , blue FIrpic, and yellow PO-01 triplet phosphorescent guests. The device with the yellow PO-01 triplet emitter exhibited the best overall performance. The most efficient yellow OLED demonstrated turn-on voltage of 4.9 V, a maximum brightness exceeding 4050 cd/m2 and current efficiency of 10.8 cd/A with power efficiency of 6.9 lm/W at 100 cd/m2.