Recent Advances in Multi-Resonance Thermally Activated Delayed Fluorescence Materials Based on B,N-Heteroarenes

In recent years, multi-resonance thermally activated delayed fluorescence (MR-TADF) materials have attracted wide attention because of their excellent photophysical properties and electroluminescent performance.By introducing electron-deficient and electron-rich centers (such as boron and nitrogen atoms) in the framework of polycyclic aromatic hydrocarbons (PAHs), the HOMO and LUMO can be separated on different atoms due to the opposite resonance effects, which can reduce the singlet-triplet energy gap (ΔEST) to achieve TADF properties.Compared with conventional donor-acceptor type TADF materials, MR-TADF materials have rigid skeletons and show short-range charge transfer characteristics, which are conducive to realizing narrowband luminescence with high color purity and high quantum efficiency, making them ideal luminescent materials and widely used in organic light-emitting diodes (OLEDs).Since the first report of MR-TADF materials based on B,N-heteroarenes in 2016, significant progress has been achieved in the development of new materials.However, a timely summary on this topic is still lacking.In this review, the design strategy and synthetic method of MR-TADF materials based on B,N-heteroarenes are summarized, and the recent advances in the development of new molecular skeletons, the backbone modification strategy to tune the properties, and a novel type of chiral MR-TADF materials are discussed.It is expected that the current review would further promote the development and application of MR-TADF materials in the future.