Amine-Directed Formation of B-N Bonds for BN-Fused Polycyclic Aromatic Multiple Resonance Emitters with Narrowband Emission.

Abstract

Despite the remarkable multiple resonance (MR) optoelectronic properties of organic nanographenes with boron and nitrogen atoms disposed para to each other, the synthetic procedures are sophisticated with low yields and the molecular skeletons are limited. Here, a new paradigm of easy-to-access MR emitter is constructed by simplifying the multiborylation through amine-directed formation of B-N bonds while introducing an additional para-positioned nitrogen atom to trigger the MR effect. The proof-of-concept molecules exhibit narrowband emissions at 480 and 490 nm, with full width at half maxima (FWHMs) of only 29 and 34 nm. The devices based on them showed external quantum efficiencies (EQE) of >33.0 %, which remained above 24.0 % even at a high brightness of 5000 cd m-2 . This is the first example of MR emitters with a B-N covalent bond, not only decreasing the synthesis difficulty but also increasing the diversity of MR skeletons for emerging new optoelectronic properties.