Synthetic and electroluminescent properties of two novel europium complexes with benzimidazole derivatives as second ligands

With two second ligands, 2-(2-pyridyl)benzimidazole (HPBM) and 1-ethyl-2-(2-pyridyl)benzimidazole (EPBM), two novel europium complexes, Eu(TTA)3HPBM and Eu(TTA)3EPBM (TTA, thenoyltrifluoroacetonato) were synthesized and applied to organic electroluminescent (EL) devices as the emitting materials. The devices of ITO/TPD/Eu(TTA)3HPBM (or Eu(TTA)3EPBM)/AlQ/Al were fabricated. The EL devices emit red light originating from these two europium complexes. The EL brightness of Eu(TTA)3EPBM is much higher than that of Eu(TTA)3HPBM. For Eu(TTA)3EPBM, a maximum luminance of 36.6 cd/m2 was achieved at 21 V.