Bipolar fluorene-cored derivatives containing carbazole-benzothiazole hybrids as non-doped emitters for deep-blue electroluminescence

Two bipolar fluorene-cored derivatives, namely BFCz and BFPCz, containing electron-transporting benzothiazole and hole-transporting carbazole moieties, are synthesized utilizing the Suzuki C-C coupling reactions, and characterized by NMR, MS and elemental analysis. These compounds possess good thermal stability with decomposition temperature up to 400 °C, and strong deep-blue emission in solution with excellent fluorescent quantum yield of over 70%. They also show high HOMO energy levels of −5.44 eV and −5.57 eV for effective hole injection and transportation from hole-transporting layer to the emitting layer. The non-doped OLEDs using these fluorene-cored derivatives as emitters by means of vacuum deposition process emit pure deep-blue electroluminescence with CIE coordinates of y ≤ 0.15, achieving maximum luminance efficiencies of 2.59 cd A−1 for BFCz, 2.87 cd A−1 for BFPCz.