An efficient and stable deep-blue oxygen-bridged triphenylborane-based fluorophore with hybridized local and charge-transfer states

Abstract

The main considerations regarding deep-blue organic electroluminescent materials entail optimizing the utilization of non-radiative triplet excitons, alongside attaining exceptional stability and minimizing efficiency roll-off, thereby enhancing their overall performance. In this work, we develop a new hybridized local and charge-transfer (HLCT) fluorophore, namely BOE, by incorporating a rigid and planar oxygen-bridged triphenylborane skeleton with anthracene and naphthalene units. The rigid and near-orthogonal molecular geometry endows it with excellent morphological stability and a rapid radiative transition rate, while maintaining deep-blue emission. Consequently, a non-doped device, exhibiting color coordinates of (0.154, 0.076), demonstrates an external quantum efficiency (EQE) of 5.14% and a small roll-off of 8.4% at 1000 cd m⁻². By using it as a host for 1-4-di-[4-(N,N-diphenyl)amino]styryl-benzene (DSA-Ph), the device shows a maximum EQE of 5.31% at a ultra-high luminance of 28 651 cd m⁻². This work offers profound guidance for the development of high-performance, novel HLCT materials that exhibit both high stability and low efficiency roll-off.