Attaching Strong Auxiliary Acceptor onto B-N-Containing Multiple Resonance Framework and Achieving Highly Efficient Electroluminescence with Ultrahigh Color Purity

The development and enrichment of organic materials with narrowband emission in longer wavelength region beyond 515 nm still remains a great challenge. Herein, a series of unique narrowband green thermally activated delayed fluorescence (TADF) emitters has been constructed based on a synthetic strategy by localized attachment of acceptor onto B-N-containing multiple resonance (MR) framework. The precise modulation of acceptor is an ingenious approach for achieving bathochromic shift and narrowband emission, simultaneously. Furthermore, an important synthetic methodology has been proposed to functionalize MR skeleton and generate a universal building block, which can be utilized to construct multifarious TADF materials with ultrahigh color purity through a simple one-step Suzuki coupling reaction. The DtCzB-TPTRZ-based organic light-emitting diode (OLED) exhibits pure green emission with Commission Internationale de L’Eclairage (CIE) coordinates of (0.23, 0.68), and achieves remarkable maximum external quantum efficiency (EQE) of 30.6% with low efficiency roll-off.