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Circularly polarized multi‐resonance thermally activated delayed fluorescence (CP‐MR‐TADF) materials, capable of achieving circularly polarized luminescence (CPL), play a crucial role in the field of 3D display. In this study, two pairs of axial chiral MR‐TADF enantiomers, (R/S)‐S‐AX‐BN and (R/S)‐SO2‐AX‐BN, are synthesized by fusing biphenyl skeletons containing sulfur/sulfone with classic B/N‐embedded polycyclic aromatic hydrocarbons. These compounds exhibit good photophysical properties with intense CPL. (R/S)‐S‐AX‐BN and (R/S)‐SO2‐AX‐BN display green photoluminescence, with peaks at 489 and 495 nm, full‐width at half‐maximum (FWHM) values of 21 and 20 nm in toluene, and dissymmetry factors (|gPL|) of 3.5 × 10−3 and 2.3 × 10−3 in doped films, respectively. Additionally, circularly polarized organic light‐emitting diodes (CP‐OLEDs) fabricated from (R/S)‐S‐AX‐BN and (R/S)‐SO2‐AX‐BN exhibit narrow electroluminescence (EL) spectra with FWHMs of 22 and 21 nm. These CP‐OLEDs achieve high maximum external quantum efficiencies of 33.5% and 31.5%, with relatively low efficiency roll‐offs. Furthermore, they exhibit high |gEL| factors of 3.3 × 10−3 and 2.2 × 10−3, respectively, representing the highest values among axial chiral analogs. This work introduces a novel approach for designing axial chiral CP‐MR‐TADF molecules and provides a reference for fabricating narrowband CP‐OLEDs with high efficiency and intense CPL. [ABSTRACT FROM AUTHOR]

The chiral materials and circularly polarized organic light‐emitting diodes (CP‐OLEDs) have potential applications in 3D display due to the generation of circularly polarized luminescence (CPL). However, achieving a combination of chirality, high efficiency, and narrowband emission for thermally activated delayed fluorescence (TADF) materials has proven to be a challenging endeavor, often involving complicated synthesis and chiral separation processes. In this study, a simple design approach is introduced by direct connection of the multiple resonance (MR) skeleton and chiral (R/S)‐1,1′‐binaphthyl units, obtaining two pairs of chiral MR‐TADF enantiomers (R/S)‐DtCzB‐OBN and (R/S)‐DtCzB‐BN without chiral resolution. These enantiomers exhibit blue‐green emissions with photoluminescence quantum efficiencies of up to 98% in doped films and full‐width at half‐maximum of 22 nm both in toluene and in the device. Furthermore, (R/S)‐DtCzB‐OBN and (R/S)‐DtCzB‐BN display symmetric CPL spectra with dissymmetry factors (gPL) of + 3.86(± 0.317) × 10−4/‐3.37(± 0.317) × 10−4 and + 7.09(± 0.233) × 10−4/‐7.74(± 0.233) × 10−4, respectively. The CP‐OLEDs based on (R/S)‐DtCzB‐OBN and (R/S)‐DtCzB‐BN exhibit impressive maximum external quantum efficiencies of 30.0% and 33.9%, as well as gEL factors of +3.40(± 0.362) × 10−4/‐3.11(± 0.362) × 10−4 and + 7.99(± 0.391) × 10−4/‐8.19(± 0.391) × 10−4, respectively. This research proposes a strategy for directly constructing chiral MR‐TADF materials for high‐performance CP‐OLEDs, avoiding complicated chiral separation. [ABSTRACT FROM AUTHOR]

Chiral boron/nitrogen doped multiple resonance thermally activated delayed fluorescence (MR‐TADF) emitters are promising for highly efficient and color‐pure circularly polarized organic light‐emitting diodes (CP‐OLEDs). Herein, we report two pairs of MR‐TADF materials (Czp‐tBuCzB, Czp‐POAB) based on planar chiral paracyclophane with photoluminescence quantum yields of up to 98 %. The enantiomers showed symmetric circularly polarized photoluminescence spectra with dissymmetry factors |gPL| of up to 1.6×10−3 in doped films. Meanwhile, the sky‐blue CP‐OLEDs with (R/S)‐Czp‐tBuCzB showed an external quantum efficiency of 32.1 % with the narrowest full‐width at half‐maximum of 24 nm among the reported CP‐OLEDs, while the devices with (R/S)‐Czp‐POAB displayed the first nearly pure green CP electroluminescence with |gEL| factors at the 10−3 level. These results demonstrate the incorporation of planar chirality into MR‐TADF emitter is a reliable strategy for constructing of efficient CP‐OLEDs. [ABSTRACT FROM AUTHOR]