Huang Y.-M.Chen, T.-Y.T.-Y.ChenChen, D.-G.D.-G.ChenLiang, H.-C.H.-C.LiangWu, C.-H.C.-H.WuLee, M.M.M.M.LeeChiu, T.-L.T.-L.ChiuJIUN-HAW LEEChiu, Y.-C.Y.-C.ChiuPI-TAI CHOUMAN-KIT LEUNG2021-08-032021-08-03202120507534https://www.scopus.com/inward/record.uri?eid=2-s2.0-85101813826&doi=10.1039%2fd0tc05145d&partnerID=40&md5=f29376db606a12124381fac57ea32421https://scholars.lib.ntu.edu.tw/handle/123456789/57580835Cbz4BzCN, a novel universal host with a long triplet lifetime, has been developed. The triplet excitons in35Cbz4BzCNcan be effectively harvested by phosphorescence and thermally activated delayed fluorescence emitters. In the 4CzIPN doped device, the best performance of a maximum current efficiency of 111.8 cd A?1, power efficiency of 86.8 lm W?1, and external quantum efficiency of 31.7% with a small efficiency roll-off of 103 cd A?1at 1000 cd m?2has been achieved.35Cbz4BzCNis also compatible with FIrpic to give sky-blue emission up to 46.3 cd A?1and with TXO-TPA to give orange-red emission up to 60.6 cd A?1efficiency. ? The Royal Society of Chemistry 2021.Energy transfer; Fluorescence; Organic light emitting diodes (OLED); Current efficiency; External quantum efficiency; Luminescence quantum efficiency; Power efficiency; Thermally activated delayed fluorescences; Triplet energy transfer; Triplet excitons; Triplet lifetimes; Quantum efficiency[SDGs]SDG7journal article10.1039/d0tc05145d2-s2.0-85101813826