Photoluminescence and electroluminescence of a series of terbium complexes

Photoluminescence and electroluminescence of a series of terbium complexes based on 1-phenyl-3-methyl-4-R-5-pyrazolone were analyzed. The first absorp tion band of the pyrazolone derivative ligands gradually shifts toward the shorter wavelength region as the R changes from an electron acceptor to an electron donor. Correspondingly, the photoluminescence quantum efficiency o f the terbium complexes increases. The neutral ligands also affect the phot oluminescence and electroluminescence of the terbium complexes. A photochem ical explanation for the influence of the R group and neutral ligand on the photoluminescence was proposed in relation to ligand-to-metal energy trans fer. The electroluminescence of the terbium complexes having a neutral liga nd comes from both the Light emitting layer and the hole transport layer wh ile the electroluminescence of the terbium complex without a neutral ligand is pure green coming solely from the light-emitting layer. It therefore de monstrates that the former have higher electron transport ability than the latter. (C) 1999 Elsevier Science S.A. All rights reserved.