Tetraborated Intrinsically Axial Chiral Multi‐resonance Thermally Activated Delayed Fluorescence Materials.

Chiral multi‐resonance thermally activated delayed fluorescence (CP‐MR‐TADF) materials hold promise for circularly polarized organic light‐emitting diodes (CP‐OLEDs) and 3D displays. Herein, we present two pairs of tetraborated intrinsically axial CP‐MR‐TADF materials, R/S‐BDBF‐BOH and R/S‐BDBT‐BOH, with conjugation‐extended bidibenzo[b,d]furan and bidibenzo[b,d]thiophene as chiral sources, which effectively participate in the distribution of the frontier molecular orbitals. Due to the heavy‐atom effect, sulfur atoms are introduced to accelerate the reverse intersystem crossing process and increase the efficiency of molecules. R/S‐BDBF‐BOH and R/S‐BDBT‐BOH manifest ultra‐pure blue emission with a maximum at 458/459 nm with a full width at half maximum of 27 nm, photoluminescence quantum yields of 90 %/91 %, and dissymmetry factors (|gPL|) of 6.8×10−4/8.5×10−4, respectively. Correspondingly, the CP‐OLEDs exhibit good performances with an external quantum efficiency of 30.1 % and |gEL| factors of 1.2×10−3. [ABSTRACT FROM AUTHOR]