Synthesis and electroluminescence properties of an organic europium complex

Abstract In order to develop new materials for red electroluminescent devices, a novel ligand, 2-phenyl-imidazo[4,5-f]1,10-phenanthroline (L), and an europium (III) complex with dibenzoylmethanate (DBM), Eu(DBM) 3 L, was synthesized. The crystal structure of Eu(DBM) 3 L was determined by single crystal X-ray diffraction. The crystal of Eu(DBM) 3 L belongs to orthorhombic, space group Pbca with cell dimensions of a =2.1655(6) nm, b =2.0834(5) nm, c =2.6469(7) nm, V =11.942(5) nm 3 , Z =8, D x =1.307 g/cm 3 . Each europium atom is coordinated with six oxygen atoms from three bidentate DBM anions and two nitrogen atoms from one bidentate L, forming a distorted square antiprism. The complex is easily evaporated and can be used as a red light emitting material. Upon improvement, the device with a structure of ITO/ N , N ′-diphenyl- N , N ′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (TPD) (40 nm)/Eu(DBM) 3 L (50 nm)/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (bathocuproine or BCP) (20 nm)/tris(8-hydroxyquinoline) aluminum (ALQ) (30 nm)/cathode gives off pure red light with luminance of 42 cd/m 2 at 16 V.