Blue electroluminescent devices made from a naphthyl-substituted benzidinederivative and rare earth metal chelates

Electroluminescent (EL) devices with a bi-layer structure were fabricated u sing N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) as a light-emitting and hole-transporting layer and a rare earth (RE) metal c helates (tris(acetylacetonato)-(mono-phenanthroline) RE(III)) (RE(ACA)(3)ph en; where, RE is Y, La or Gd), as the electron-transporting layer. For the device using the Gd complex, blue EL emission with a maximum luminance of o ver 1000 cd/m(2) was achieved at similar to 22 V. The effects of using the yttrium and lanthanide complexes instead of the Gd complex on the EL emissi on spectra were discussed. (C) 2000 Elsevier Science S.A. All rights reserv ed.