Nonconjugated hybrid of carbazole and fluorene: a novel host material for highly efficient green and red phosphorescent OLEDs.

[structure: see text] A novel host material for efficient green and red electrophosphorescence devices is obtained by adopting the new molecular strategy of nonconjugated linkage of carbazole and fluorene moieties. The new host combines characteristics of both carbazole and fluorene, giving a large-gap host material suitable for green and red phosphorescent OLEDs. Green and red phosphoresecent OLEDs with external quantum efficiencies up to 10% have been achieved with this new host material.