Ortho ‐Diboron Blue Multiple Resonance Thermally Activated Delayed Fluorescence Material

ABSTRACT Diboron‐based multi‐resonance thermally activated delayed fluorescence materials (MR‐TADF) are pivotal for advanced display applications, whereas ortho ‐diboronated derivatives remain scarce. Furthermore, the reported ortho ‐diboronated compounds demonstrate a significant bathochromic shift to enable long‐wavelength emission. Herein, we propose a strategy of fusing an isolated ortho ‐diboron moiety into the nitrogen/ boron/ oxygen skeleton to partially offset frontier molecular orbitals, which reduces the electronic coupling effect, and the intramolecular charge transfer state is modulated to achieve pure blue emission peaking at 461 nm in toluene with narrow emission. Notably, the TADF material‐sensitized organic light‐emitting diode achieves a maximum external quantum efficiency of 34.9% with a low efficiency roll‐off at a luminance of 1000 cd·m −2 . This study provides instructive insights for the realization of blue emission and full‐spectrum materials in ortho ‐diboronated architectures.