Fluorenes substituted with fluorophenyl, difluorophenyl or trifluorophenyl fragments as materials for organic light emitting diodes

Abstract

9,9-Diethylfluorenes substituted with two fluorophenyl, difluorophenyl or trifluorophenyl fragments were synthesized by the multi-step synthetic rout. The materials were characterized by 1H NMR spectroscopy, mass spectrometry, differential scanning calorimetry and thermogravimetric analyses. Some of the electro-active derivatives could form thin amorphous films and were tested as solution processed hole transporting layers in organic light- emitting diodes with Alq3 as the emitter and electron transporting material. Some of the electroluminescent devices demonstrated turn voltage of 5.5 V, a maximal photometric efficiency of about 1.0 cd/A and maximum brightness exceeding 960 cd/m2.