Abstract
New carbazole- and phenylindole-based low molecular weight derivatives were synthesized and characterized. The compounds could form homogeneous amorphous materials (layers). The electron photoemission spectra of the layers of the synthesized compounds showed ionization potentials of 5.75-5.95 eV. The derivatives were tested as host materials in green and blue phosphorescent OLEDs with tris(2-phenylpyridine)iridium(III) and iridium(III)[bis(4,6- difluorophenyl)-pyridinato-N,C2′]picolinate, correspondingly, as the guests. One of the green OLEDs demonstrated current efficiency of 20.9 cd/A and power efficiency of 6.8 lm/W at 100 cd/m 2 . An efficient blue OLED showed a maximum brightness of 1160 cd/m 2 , and current efficiency of 9.4 cd/A with power efficiency of 4 lm/W at 100 cd/m 2 . © 2012 Elsevier B.V. All rights reserved.