1-methyl-2-(anthryl)-imidazo[4,5-f] [1,10]-phenanthroline: A highly efficient electron-transport compound and a bright blue-light emitter for electroluminescent devices

A new organic blue-light emitter 1-methyl-2-(anthryl)-imidazo[4,5-f][1,10]- phenanthroline (1) has been synthesized and fully characterized. The utility of compound 1 as a blue-light emitter in electroluminescent (EL) devices has been evaluated by fabricating a series of EL devices A where compound 1 functions as an emitter. The EL spectrum of device series A has the emission maximum at 481 nm with the CIE (Commission Internationale de l'Eclairage) color coordinates 0.198 and 0.284. The maximum luminance of devices in series A is 4000 cd m ^-2 and the best external quantum efficiency of device series A is 1.82%. The utility of compound 1 as an electron injection-electron transport material has been evaluated by constructing a set of EL devices B where 1 is used as either the electron-injection layer or the electron injection-electron transport layer. The performance of device series B is compared to the standard device in which Alq₃ (tris(8-hydroxyquinoline) aluminum) is used as the electron injection-electron transport layer. The experimental results show that the performance of 1 as an electron injection-electron transport material is considerably better than Alq₃. The stability of device series B is comparable to that of the standard Alq₃ device. The excellent performance of 1 as an electron injection/transport material may be attributed to the strong intermolecular interactions of 1 in the solid state as revealed by single-crystal X-ray diffraction analysis. In addition, compound 1 is a colorless material with a much larger highest occupied molecular orbital-lowest unoccupied molecular (HOMO-LUMO) gap than Alq₃, which renders it potentially useful for a wide range of applications in EL devices.