Tunable Dipolar Acenaphthopyrazine Derivatives Containing Diphenylamine

A series of acenaphthopyrazine derivatives containing diphenylamine were synthesized. These compounds are amorphous with glass transition temperatures ranging from 95 to 155 °C. They are highly fluorescent with emission in green-yellow to red region. The dipolar character of the compounds results in prominent solvatochromic effect on the emission spectra. Two-layer electroluminescent devices were fabricated using these compounds as hole-transporting and emitting materials, and 1,3,5-tris( N -phenylbenzimidazol-2-yl)benzene (TPBI) or tris(8-hydroxyquinoline)aluminum (Alq 3 ) as the electron-transporting layer. Multilayer devices were also fabricated using the compounds as the emitting materials. Green-yellow-emitting devices exhibiting good performance (e.g., λ em = 560−570 nm; η ext = 2.0−2.6%; η p = 2.3−3.2 lm/W; η c = 6.5−8.3 cd/A at a current density of 100 mA/cm 2 ) can be achieved in multilayered devices.