3,3'‐Substituted Binaphthol‐Based Axially Chiral MR‐TADF Enantiomers for Solution‐Processed Circularly Polarized Organic Light‐Emitting Diodes (CP‐OLEDs) With External Quantum Efficiency Over 28%

ABSTRACT The chiral multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters and circularly polarized organic light‐emitting diodes (CP‐OLEDs) present great potential for applications in 3D display. However, achieving the simultaneous combination of narrowband emission, high efficiency, and chirality in solution‐processable MR‐TADF materials through simple methods has consistently proven challenging. The ( R / S )‐binaphthol chiral unit has been employed in the development of chiral MR‐TADF emitters owing to its low cost, easy accessibility, and facile modification. However, current emitters based on the ( R / S )‐binaphthol unit are predominantly prepared through modification at the 2,2’‐position, which suffers from significant steric hindrance, low synthetic yields, and potential adverse effects from intramolecular interactions. Herein, a simple design approach is introduced by directly linking MR‐TADF units at the 3,3’‐position of the ( R / S )‐binaphthol, obtaining chiral enantiomers, ( R / S )‐DBNP, in high yield without chiral resolution. Notably, the solution‐processed CP‐OLED based on R ‐DBNP achieved a maximum external quantum efficiency (EQE) of 28.1% and an electroluminescence dissymmetry factors ( |g EL | ) value of 2.9 × 10 −3 . The Q‐factor (|EQE × g EL |) of CP‐OLED is determined to be 8.1 × 10 −4 , which is considerable among solution‐processed CP‐OLEDs based on small molecules. This simple method reveals the potential for constructing chiral MR‐TADF materials for high‐performance solution‐processed CP‐OLEDs, avoiding complicated chiral separation.