Electroluminescence of a novel terbium complex

We describe efficient electroluminescence from a terbium complex, tris-(1-phenyl-3-methyl-4-isobutyryl-5-pyrozolone) -bis(triphenyl phosphine oxide) terbium (PTT). The; green-emitting material possesses much higher photoluminescence efficiency compared to the commonly used green Light emitter, 8-hydroxyquinoline aluminum (ALQ). The rarely observed emission from the hole transport layer, N; N'-bis (3-methylphenyl)-N, N'-diphenyl-benzidine (TPD) bf the device ITO/TPD/PTT/Al proves that PTT also is a good electron transporting material. The ITO/TPD/PTT/ALQ/Al device shows luminance up to 920 cd/m(2) at a drive voltage of 18 V and a luminous efficiency of 0.51 lm/W at a current density of 0.70 mA/cm(2), which are up to now the highest among devices using rare-earth complex materials as emitters. (C) 1998 American Institute of Physics.