Chiral Through‐Space Charge‐Transfer Thermally Activated Delayed Fluorescent Emitter with Multiple Stereogenic Centers

Abstract

ABSTRACT The development of high‐performance circularly polarized thermally activated delayed fluorescence (CP‐TADF) emitters featuring through‐space charge‐transfer (TSCT) transitions is fascinating yet challenging due to the difficulty in balancing efficiency, dissymmetry factors, and structural diversity. Here, we report the first helical‐configuration integrated TSCT‐type CP‐TADF emitter, which adopts a dual‐spiro‐locked face‐to‐face acceptor/donor/acceptor scaffold. This sandwiched design not only enables degenerate energy states via multi‐channel TSCT transitions but also incorporates multiple stereogenic centers, resulting in an exceptionally small singlet–triplet energy gap of 0.04 eV, a high reverse intersystem crossing rate of >10 6 s − 1 , and near‐unity photoluminescence quantum yields (>93%), accompanied by a benchmark high photoluminescence dissymmetry factor (| g PL |) of 4.4 × 10 − 3 among such TSCT‐type emitters. When applied as an emitter in organic light‐emitting diodes (OLEDs), this molecule achieves a maximum external quantum efficiency (EQE max ) of 27.4% with suppressed efficiency roll‐off and strong electroluminescence dissymmetry (| g EL | ≈ 3.2 × 10 − 3 ). When used as a sensitizer for a multiple‐resonance TADF emitter, it enables an impressive maximum external quantum efficiency (EQE max ) of 38.4% while maintaining high | g EL | (≈ 3.0 × 10 − 3 ). This work greatly diversifies the structural frameworks of TSCT‐type CP‐TADF emitter with improved performance.