Fluorene-Carbazole Dendrimers: Synthesis, Thermal, Photophysical and Electroluminescent Device Properties

Novel hole-transporting dendrimeric molecules containing dioctylfluorene, spirobi(fluorene) and spiro(cylododecane-fluorene) as the core unit and different numbers of carbazole and thiophene moieties as the peripheral groups are synthesized. All the dendrimers are characterized by H-1 NMR, C-13 NMR, FTIR, UV-vis, PL spectroscopy, and MALDI-TOF. They are thermally stable with high glass transition and decomposition temperatures and exhibit chemically reversible redox processes. They are used as the hole-transporting layer (HTL) material for multilayer organic light emitting diodes (OLEDs) with a low turn-on voltage of around 2.5 V and a bright green emission with a maximum luminance of around 25400 cd m(-2).