Abstract
Oligoethers containing electroactive carbazolyl, indolyl or 2-phenylindolyl fragments were synthesized and characterized by NMR spectroscopy, elemental analysis and gel permeation chromatography. The oligomers represent amorphous materials of high thermal stability with glass transition temperatures of 107-161°C. The electron photoemission spectra of layers of the synthesized oligomers showed ionization potentials of 5.9-5.95 eV. Some of the derivatives were tested as host materials in phosphorescent OLEDs with iridium(III) [bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate as the guest. The device based on oligomer containing carbazolyl fragments exhibited the best overall performance with a turn-on voltage of 3.5 V, maximum power efficiency of 4.1 lm/W and maximum brightness of 937 cd/m 2 . © 2011 Wiley Periodicals, Inc.