Macrocyclic Dual‐ and Tetra‐Borated Multi‐Resonance Thermally Activated Delayed Fluorescence Materials Based on Tetraazacyclophane

Abstract

ABSTRACT In multiple‐resonance‐induced thermally activated delayed fluorescence (MR‐TADF) materials with a meta B‐π‐B configuration, most studies mainly focused on linear multi‐boron frameworks. In this study, we report two macrocyclic dual‐ and tetra‐borated MR‐TADF materials based on tetraazacyclophane (DPN2B and DPN4B). By rationally selecting boron sources and reaction conditions, one‐pot double and quadruple borylation reactions were achieved. In toluene, DPN2B and DPN4B exhibit deep blue narrowband emission peaking at 451 and 442 nm, with full widths at half maximum of 22 and 25 nm, respectively. Solution‐processed organic light‐emitting diodes (OLEDs) based on DPN2B and DPN4B show pure‐blue electroluminescence with peaks at 458 and 452 nm, with maximum external quantum efficiencies of 6.4% and 4.0%, respectively. The DPN2B‐based device achieves Commission Internationale de l’Éclairage coordinates of (0.14 and 0.07). This work provides a practical macrocyclic molecular design strategy for developing multi‐borated MR‐TADF emitters and OLEDs.