New oligomers containing pendant 4-aryl-7-phenylfluorene units as efficient charge transporting materials for OLEDs

WOS:000413880500088Monomers and oligomers containing electronically isolated 4-aryl-7-phenylfluorene fragments have been synthesized by the multi-step synthetic route. The materials were characterized by thermogravimetric analysis, differential scanning calorimetry and electron photoemission technique. The oligomers represent materials of very high thermal stability having initial thermal degradation temperatures in the range of 402e412 C. The glass transition temperatures of the amorphous oligomers were in the rage of 97e129 C. The electron photoemission spectra of thin layers of the oligomeric materials showed ionization potentials in the range of 5.7e6.1 eV. Hole injecting/transporting properties of the electroactive oligomers were tested in the structures of organic light emitting diodes with tris(quinolin-8-olato) aluminium as a green emitter. The device containing hole-transporting material with 4-biphenyl-7- phenylfluorene electrophores exhibited the best overall performance with low turn on voltage of 4.4 V, high current efficiency exceeding 3.6 cd/A and maximum brightness exceeding 3200 cd/m2Biochemijos katedraKauno technologijos universitetasLietuvos sveikatos mokslų universitetas. Medicinos akademijaVytauto Didžiojo universiteta