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

Abstract

AbstractRecently, 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 π–π 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 (ΔEST) of 0.03 eV and delayed fluorescence lifetime of 1.1 µs, as well as intense circularly polarized luminescence with dissymmetry factors (|gPL|) of about 1.9 × 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 gEL values of +1.5 × 10−3 and −2.0 × 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.