Polyethers containing pendent 9-aryl[3,3′]bicarbazolyl fragments as hole-transporting materials for OLEDs

Electro-active polymers containing pendent 9-aryl[3,3′]bicarbazolyl fragments were synthesized and characterized. The materials were examined by various techniques including thermogravimetry, differential scanning calorimetry, UV and fluorescence spectrometry as well as electron photoemission technique. The electron photoemission spectra of the layers showed the ionization potentials of 5.2-5.5 eV. The synthesized polymers were tested as hole-transporting materials in bilayer OLEDs with Alq3 as the emitter. The devices with polymers containing 9,9-diethylfluorenyl or p-tolyl substituted bicarbazolyl fragments exhibited the best overall performance with turn-on voltage of about 3 V, a maximum photometric efficiency of 3.6 cd/A and maximum brightness of ca. 14,000 cd/m2.