Carbazole- and phenylindole-based new host materials for phosphorescent organic light emitting diodes

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/m2. An efficient blue OLED showed a maximum brightness of 1160 cd/m2, and current efficiency of 9.4 cd/A with power efficiency of 4 lm/W at 100 cd/m2.

► Derivatives with phenylindolyl and carbazolyl fragments were synthesized.
► The compounds were tested as host materials in phosphorescent OLEDs.
► Green devices demonstrated current efficiency of about 21 cd/A at 100 cd/m2.
► Blue OLEDs devices showed current efficiency of 9.4 cd/A at 100 cd/m2.