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

Abstract

A new class of cis-stilbene/fluorene spiro hybrid systems with paired diphenylamino donor and cyano, N-phenylbenzimidazole, dimesitylboranyl, or β,β-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 (α-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 α-NPB/tris(8-hydroxyquinoline)aluminum bilayer devices.