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

Abstract

Chiral multi‐resonance thermally activated delayed fluorescence (CP‐MR‐TADF) materials hold promise for circularly polarized organic light‐emitting diode (CP‐OLED) and 3D display. 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 frontier molecular orbitals. Due to the heavy‐atom effect, sulfur atoms are introduced to accelerate the reverse intersystem crossing process and increase efficiency of molecules. R/S‐BDBF‐BOH and R/S‐BDBT‐BOH manifest ultra‐pure blue emission peaking at 458/459 nm with full width at half maximum of 27 nm (0.16 eV), 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 external quantum efficiency of 30.1% and |gEL| factors of 1.2 × 10‐3.