Novel starshaped molecules based on fluorene

A series of starshaped molecules with different cores such as benzene, triphenylbenzene and triphenylamine and fluorene-moieties as side arms were synthesized by suzuki cross-coupling. These low molecular weight compounds form stable glasses and are easily obtained in high purity by column chromatography and sublimation. Variation of the alkyl chain length in the 9 position of the fluorenes and changing the core have a great influence to their glassforming abilities and the glass transition temperature, which range from 57 degreesC to 118 degreesC. All starshaped molecules show blue emission, which can be fine-tuned by the choice of the cores. A first two-layer device with the configuration ITO/NPB/TFPB-Bu/Ca was prepared by vacuum evaporation and shows an external quantum efficiency of 1.2 % at 10 V.