Synthesis and characterization of pyrene-centered starburst oligofluorenes

A series of starburst materials (T1-T3) based on a pyrene core with four oligofluorene arms of different length have been synthesized and characterized. The starburst materials show good film forming ability and sky blue fluorescence. Electroluminescent devices take on a stable blue emission and the device performance increases with an increase in arm length. The single-layered device made of T3 has a maximum brightness of over 2700 cd·m^-2 and a maximum current efficiency of 1.75 cd·A^-1, which is among the best in starburst material devices. The morphology of T1-T3 has been studied by atomic force microscopy. The star-burst oligofluorenes with different arm lengths show a distinctive texture, which indicates the size dependent morphology of the starburst materials.