Abstract
Branched derivatives containing diphenylsilane core and pendent carbazol-9-yl fragments were synthesized and characterized. The compounds represent amorphous materials of high thermal stability with glass transition temperatures of 54-93 °C and thermal decomposition starting at temperatures above 391 °C. The electron photoemission spectra of layers of the synthesized compounds showed ionization potentials of ca 5.9 eV. 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 with the host derivative containing four isolated carbazolyl fragments exhibited the best overall performance with maximum current efficiency of 16.4 cd/A and maximum brightness exceeding 200 cd/m 2 . © 2010 Elsevier B.V. All rights reserved.