Orange phosphorescent organic light-emitting diodes using new spiro [benzoanthracene-fluorene]-type host materials

New spirobenzoanthrcene-type orange phosphorescent host materials, 9-(spiro[benzoanthracene-7,9'-fluorene]-2'-yl)-9H-carbazole and 9-(spiro[benzoanthracene-7,9'-fluorene]-3-yl)-9H-carbazole, with stable efficiency roll-off, were prepared by an Ullmann coupling reaction of 2'-bromo-spiro[benzoanthracene-7,9'-fluorene] and 3-bromo-spiro[benzoanthracene-7,9'-fluorene] respectively, with carbazole. Orange phosphorescent organic light-emitting diodes with the configuration of indium tin oxide/N,N'-diphenyl-N,N'-bis-[4-(phenyl-m-tolylamino)-phenyl]1-biphenyl-4,4'-diamine/N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine/Host:Ir(pq)(2)acac/2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline/tris(8-hydroxyquinoline)aluminum/LiF/A1 were developed using spiro[benzoanthracene-fluorene]-type carbazole derivatives as a host material and Ir(pq)(2)acac as a dopant. A device obtained from 9-(spiro[benzoanthracene-7,9'-fluorene]-2'-yl)-9H-carbazole doped with 3% Ir(pq)(2)acac showed an orange color purity of (0.599, 0373) and an efficiency of 14.74 cd/A at 6.0 V. The overall result is a device with an external quantum efficiency (EQE) >8.93% at high brightness but an operating voltage of <6.0 V. (C) 2012 Elsevier Ltd. All rights reserved.