New Quinoxaline‐Based Blue Emitters: Molecular Structures, Aggregation‐Induced Enhanced Emission Characteristics and OLED Application

Three new deep blue light emitters, bearing quinoxaline with different substituents (biphenyl/pyrene) at the 1- or 2-position, were synthesized by a Pd-catalysed coupling reaction in high yields, and were fully characterized by 1H/13C NMR spectroscopy, single crystal X-ray diffraction, and high-resolution mass spectrometry (HRMS). The designed molecules exhibit good thermal stability (Tg > 452 oC). Single crystal X-ray diffraction indicated the compounds containing pyrene units exhibiting π-π stacking, and thus this family of compounds exhibited intramolecular charge transfer (ICT) and non-typical and aggregation-induced enhanced emission (AIEE) characteristics, possessing blue emission both in solution and in the aggregation (solid) state. Furthermore, a selected deep blue emitter was utilized as the emitting layer for the fabrication of doped organic light-emitting diode (OLED) devices, which afforded a deep blue electroluminescence (EL) peak at 428 nm with a narrow full width at half maximum (FWHM) of 57 nm, and the Commission Internationale de L'Eclairage (CIE) chromaticity coordinates of (0.15, 0.06).