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 7.8×10⁷  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.