Abstract Multi‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters have shown promise for achieving full‐color emission with a high efficiency and a narrow band. However, the development of MR‐TADF materials with both high efficiency and deep‐blue emission for organic light‐emitting diode (OLED) remains a significant challenge. Herein, a B/N‐based MR core and a indolocarbazole group are interlocked in 3D mode to induce intramolecular interaction between both, culminating in the development of the target emitter, DPABN‐ICz. Notably, DPABN‐ICz demonstrates a remarkable deep‐blue emission, peaking at 445 nm, with a small full width at half maximum (FWHM) of 19 nm and a Commission Internationale de L'Eclairage (CIE) y coordinate of 0.06. Interestingly, DPABN‐ICz exhibits an enhanced oscillator strength of 0.2975, resulting in an impressive photoluminescence quantum yield of 94%. Furthermore, the sensitized OLED achieves a high maximum external quantum efficiency of 31.4%, and a narrow electroluminescence with a small FWHM of 27 nm and the CIE coordinates of (0.153, 0.055), closely aligning with the BT.2020 deep‐blue emission standard.
Luo et al. (Fri,) studied this question.