Spirally configured cis-stilbene/fluorene hybrids as ambipolar, fluorescent materials for organic light emitting diode applications

A new class of cis-stilbene/fluorene spiro hybrid systems with paired diphenylamino donor and cyano, N-phenylbenzimidazole, dimesitylboranyl, or beta,beta-diphenylethenyl acceptor units was synthesized as ambipolar materials for organic light-emitting diode applications. When coupled with hole transporting 4,4'-bis(1-naphthylphenylamino)-1,1'-biphenyl (alpha-NPB) and electron transporting 2,2',2 ''-(1,3,5-benzenetriyl)- tris(1-phenyl-1-H-benzimidazole) layers, they served as one of the best bluish green and pure green emitting layers with excellent external quantum efficiencies of 3.9-5.2%, electroluminescent brightness of 2202-3069 cd m(-2), luminance efficiencies of 11.0-15.8 cd A(-1), and power efficiencies of 5.7-6.6 lm W-1 at 20 mA cm(-2), which were about 2-3 times better than those based on standard alpha-NPB/tris(8-hydroxyquinoline) aluminum bilayer devices.