High-Performance Solution-Processed Nondoped Circularly Polarized OLEDs with Chiral Triptycene Scaffold-Based TADF Emitters Realizing Over 20% External Quantum Efficiency

Recently, circularly polarized organic light-emitting diodes (CP-OLEDs) fabricated with thermally activated delayed fluorescence (TADF) emitters are developed rapidly. However, most devices are fabricated by vacuum deposition technology, and developing efficient solution-processed CP-OLEDs, especially nondoped devices, is still a challenge. Herein, a pair of triptycene-based enantiomers, (S,S)-/(R,R)-TpAc-TRZ, are synthesized. The novel chiral triptycene scaffold of enantiomers avoids their intermolecular pi-pi stacking, which is conducive to their aggregation-induced emission characteristics and high photoluminescence quantum yield of 85% in the solid state. Moreover, the triptycene-based enantiomers exhibit efficient TADF activities with a small singlet-triplet energy gap (Delta E-ST) of 0.03 eV and delayed fluorescence lifetime of 1.1 mu s, as well as intense circularly polarized luminescence with dissymmetry factors (|g(PL)|) of about 1.9 x 10(-3). The solution-processed nondoped CP-OLEDs based on (S,S)-/(R,R)-TpAc-TRZ not only display obvious circularly polarized electroluminescence signals with g(EL) values of +1.5 x 10(-3) and -2.0 x 10(-3), respectively, but also achieve high efficiencies with external quantum, current, and power efficiency up to 25.5%, 88.6 cd A(-1), and 95.9 lm W-1, respectively.

Automated summary

Recently, CP-OLEDs with TADF emitters have been rapidly developed, but efficient solution-processed devices remain challenging. Synthesizing novel triptycene-based enantiomers, (S,S)-/(R,R)-TpAc-TRZ, led to efficient TADF activities and intense circularly polarized luminescence. The solution-processed nondoped CP-OLEDs based on these enantiomers exhibited high efficiency in terms of quantum efficiency, current efficiency, and power efficiency.