Efficient single layer organic light emitting diodes based on a Terbium pyrazolone complex

Single layer devices of the organolanthanide complex, terbium Tris-(1-pheny l-3-methyl-4-(tertiarybutyryl)pyrazol-5-one)triphenylphosphine oxide [(tb-P MP)(3)Tb(Ph3PO)] were made to investigate its light emission and current tr ansporting properties. Ca and Mg layers were used for the cathode contact. A higher current density at much lower voltages can be attained with Ca cat hode because of the enhanced electron injection. The maximum brightness of a single layer device with a Ca cathode was 226 cd/m(2) at 18 V and the bes t electroluminescence (EL) efficiency was 0.67 cd/A at 14 V and 70 cd/m(2). (C) 2001 Elsevier Science B.V. All rights reserved.