New quinoxaline-based blue emitters: molecular structures, aggregation-induced enhanced emission characteristics and OLED application

Three new, deep blue light emitters, containing quinoxaline with differing substitution positions (1‐ or 2‐ position) pyrene (biphenyl) moieties, were synthesized by a Pd‐catalysed coupling reaction in high yield, and were fully characterized by ¹H/¹³C NMR spectroscopy, single crystal X‐ray diffraction, and high‐resolution mass spectrometry (HRMS). The designed molecules exhibited good thermal stability (Tg > 452 oC). Single crystal X‐ray diffraction indicated that 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 fabricating of doped OLED devices, which afforded a deep blue electroluminescence (EL) peak at 428 nm with a narrow FWHM of 57 nm, and the Commission Internationale de L'Eclairage (CIE) chromaticity coordinates of (0.15, 0.06).