OLEDs based on 5Cz-TRZ as blue dopant and mCBP as host exhibit high maximum external quantum efficiency of 29.3%, and good device stability with estimated T90 about 600 h for 1,000 cd m-2. Also, 5Cz-TRZ exhibits an extremely low efficiency roll‐off mainly due to the fast rate of reversed intersystem crossing. For example, the efficiency remains at 28.6% at 1000 cd m-2 and still as high as 27.0% at 5000 cd m-2, corresponding to a 2.3% decrease in EQE even at high brightness intensities.
5Cz-TRZ features the following as a TADF material.