Boron‐Oxygen Covalent Fusion Enables Narrowband Deep‐Red CP‐OLEDs Based on BODIPY Emitters

ABSTRACT Realizing solution‐processable deep‐red circularly polarized organic light‐emitting diodes (CP‐OLEDs) with both intense CP and high color purity remains a formidable challenge. Herein, we report the first solution‐processed narrowband deep‐red circularly polarized hyperfluorescence OLEDs based on a helically chiral boron‐dipyrromethene emitter. Intramolecular boron–oxygen (B–O) covalent fusion simultaneously regulates molecular conjugation and conformational rigidity, thereby suppressing excited‐state structural relaxation and vibronic coupling while preserving efficient deep‐red emission. As a result, BDP‐BO exhibits deep‐red emission at 654 nm with a high photoluminescence quantum yield of 71% and an ultranarrow emission bandwidth of 34 nm (0.10 eV). The corresponding P ‐ and M ‐enantiomers display excellent chiroptical activity, with a luminescence dissymmetry factor (| g lum |) up to 3.54 × 10 −3 and a circularly polarized luminescence brightness ( B CPL ) of 49 M −1 cm −1 . Exploiting these merits, the M ‐ BDP‐BO ‐based device delivers deep‐red electroluminescence (EL) within the National Television System Committee color gamut, a maximum external quantum efficiency of 2.6%, and a large EL dissymmetry factor (| g EL |) of 5.49 × 10 −3 . This work establishes B–O covalent fusion as an effective strategy for simultaneously regulating molecular conjugation and conformational rigidity, providing a versatile platform for high‐performance solution‐processed deep‐red CP‐OLEDs.