One-shot borylation synthesis of multiple resonance (MR) blue emitters via fusing benzofuran fragments within B/N skeletons

Abstract

Establishing a simple molecular design and synthesis strategy for blue multi-resonance (MR) fluorescence emitters remains a crucial yet challenging task. Herein, we develop two MR blue emitters, namely OBN-1 and OBN-2, through fusing benzofuran fragments within B/N skeletons based on a one-shot borylation synthesis method. These MR blue emitters show new π-conjugated structures with alternate arrangements of HOMO–LUMO and extensive overlap distributions of HOMO–LUMO, and high oscillator strengths (f) as well as high photoluminescence quantum yields (PLQYs) up to 99.4% and 99.9% in toluene. Peripheral auxiliary aryl/heteroaryl amine substituents are introduced into MR emitters for reduction of intermolecular interactions. The electroluminescent devices utilizing OBN-1 and OBN-2 as fluorescent emitters show high external quantum efficiencies (EQEs) of 5.9% and 5.7% and blue emissions at 458 and 455 nm with CIE coordinates of (0.135, 0.155) and (0.139, 0.121). This work presents a one-pot synthesis method to construct a new type of MR core structure for the development of high-performance blue MR emitters.