High‐Efficiency Circularly Polarized Electroluminescence from TADF‐Sensitized Fluorescent Enantiomers

A couple of fluorescent enantiomers, which are suitable for the emitters of high‐efficiency TADF‐sensitized CP‐OLEDs, have been developed. The enantiomers show configurational stability, high PLQY of 98 %, large k r of 7.8×10 7  s −1 , and intense CPL activities with |g lum | values of about 2.5×10 −3 . Notably, by using matchable TADF sensitizer, the enantiomers were then exploited as emitter to fabricate CP‐OLEDs. The TADF‐sensitized CP‐OLEDs not only show mirror‐image CPEL activities with g EL values of +1.8×10 −3 and −1.4×10 −3 , but also display fast start‐up featuring with low V T of 3.0 V as well as driving voltage of 4.8 V at 10 000 cd m −2 . Meaningfully, the TADF‐sensitized fluorescent devices show high EQE max of 21.5 % and extremely low efficiency roll‐off, whose EQEs are 21.2 % and 15.3 % at 1000 and 10 000 cd m −2 , respectively. The obtained EQEs are comparable to those of CP‐TADF emitters, which provides a promising perspective to break through the EL efficiency limit of CP‐FL emitters.