Terphenyl-modified diboron embedded multi-resonance thermally activated delayed fluorescence emitters with high efficiency

Nitrogen/boron-based multi-resonance thermally activated delayed fluorescence (MR-TADF) materials offer advantages in terms of high photoluminescence quantum yield (PLQY) and narrowband emission, making them highly promising for display applications. Represented by ν-DABNA, diboron MR-TADF materials demonstrate the potential for high-efficiency narrowband emission. However, their large planar structures are susceptible to intermolecular interactions, thus increasing the complexity of device fabrication. In this research, our objective was to enhance the anti-aggregation capabilities of the diboron-based ν-DABNA by incorporating sterically hindered terphenyl groups. We synthesized two luminescent materials, DTPF-ν-DABNA and DTP-ν-DABNA, with intermolecular distances exceeding 4 Å in single-crystal stacking, significantly inhibiting intermolecular interactions. Both materials achieved an external quantum efficiency (EQE) exceeding 30% and full width at half maximum (FWHM) of no more than 22 nm, demonstrating characteristics of high-efficiency narrowband emission. Our research provides a straightforward and practical method to obtain MR-TADF materials with high device efficiency and low sensitivity to doping concentration.