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 degreesC. 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., lambda(em) = 560-570 nm; eta(ext) = 2.0-2.6%; eta(p) = 2.3-3.2 Im/W; eta(c) = 6.5-8.3 cd/A at a current density of 100 mA/cm(2)) can be achieved in multilayered devices.