Symmetric Multi-Resonant TADF Emitters via Chiral Space Conjugation Toward Strong Chiroptical Responses and Narrowband Green Circularly Polarized Electroluminescence.

Developing thermally activated delayed fluorescence (TADF) materials with excellent chiroptical and photophysical properties is crucial for advancing optoelectronic applications. Herein, a chiral space conjugation strategy incorporating a typical [2.2]paracyclophane unit is proposed to construct a highly efficient chiral multi-resonant (MR) TADF emitter, R(S)-PCP-DBNO. Guided by the symmetry-matching rule, the molecular design achieves balanced contribution and optimal alignment of transition electric and magnetic dipole moments, resulting in a strong chiroptical response with a dissymmetry factor (|g|) exceeding 0.02. Meanwhile, owing to the special through-space conjugation, the enantiomer exhibits pure green emission with a peak at 526 nm, a narrow full-width at half-maximum of 26 nm, a Commission Internationale de I'Éclairage y coordinate of 0.70 and a quantum efficiency of 0.94 in toluene solution. When integrated into sensitized organic light-emitting diodes (OLEDs), R(S)-PCP-DBNO delivers a maximum luminance up to 241k cd·m, a maximum external quantum efficiency up to 29.4% and minimal efficiency roll-off. Furthermore, the devices demonstrate distinct circularly polarized electroluminescence, confirming the utility of this strategy for chiral MR-TADF emitters and circularly polarized OLEDs with simultaneous color purity, efficiency, and chiroptical functionality.