Efficient Deep-Blue TADF Emission from Multiheteroatom-Doped Polycyclic Aromatic Hydrocarbon Embedded with Dual B─O Covalent Bonds.

Boron-doped polycyclic aromatic hydrocarbons (PAHs) have demonstrated exceptional potential in the development of high-performance organic light-emitting diodes (OLEDs). In this study, we propose a novel strategy for constructing PAH structures with thermally activated delayed fluorescence (TADF) properties by incorporating boron-oxygen (B─O) covalent bonds, as opposed to doping isolated boron atoms. The newly designed multiheteroatom-doped molecule, BNB-OPTZ, was synthesized via a demethylation-directed, lithium-free methodology, achieving an impressive one-pot yield exceeding 80%. BNB-OPTZ adopts a symmetric, distorted semi-planar rigid conformation. Theoretical calculations reveal its long-range charge transfer characteristics. The molecule exhibits deep blue emission with a peak wavelength of 441 nm in toluene solution, accompanied by CIE coordinates of (0.14, 0.05). Notably, the blue OLED device using BNB-OPTZ achieved a remarkable external quantum efficiency of 23.1%. These findings suggest that the incorporation of B─O covalent bonds into multiheteroatom-doped PAH frameworks offers a promising design strategy for advancing PAH-based blue-light OLED applications.