The characteristics of the monomer fluorene derivative in electroluminescent devices

Abstract

The fluorene derivative included in polymers has been reported to emit highly efficient blue luminescence electroluminescent devices (ELDs). The monomer fluorene derivative is advantage of over the polymers in term of easy processability and long term stability. The characteristic emission peaks observed at around 500nm from the devices with and without 8-Hydroxyquinoline aluminum salt (Alq(3)) was studied. The fluorescence from 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) and fluorene derivative did not extend over 500nm. The low energy transition at 500nm observed from the ELDs, was very similar with the results obtained from the device of ITO/CuPc/TPD/PBD/Al. The characteristic low energy peaks can be resulted from the local electric field generated by the space charge under the high electric field. The device stability was improved when the PBD layer layered over the fluorene derivative. The improvement can be correlated with the smooth surface of PBD over the fluorene derivative.