Highly-efficiency red-emitting platinum (II) complexes containing 4′-diarylamino-1-phenylisoquinoline ligands in polymer light-emitting diodes: Synthesis, structure, photoelectron and electroluminescence

Heteroleptic cyclometalated platinum (II) complexes bearing diarylamino-functionalized 1-phenylisoquinoline derivatives as primary ligand and acetyl acetonate as ancillary ligand were prepared and characterized. Single-crystal X-ray diffraction revealed that platinum (II) (4-(isoquinolin-1-yl)-N,N-diphenylbenzenamine-N,C-2') (2,4-pentanedionato-O,O) displayed square planar molecular geometry with Pt center dot center dot center dot Pt separation of 6.328 and 6.275 angstrom. The platinum (II) complexes displayed good thermal and morphological stability, as well as intense ligand-centered fluorescence and pi-pi* phosphorescence at 298 K, as well as strong phosphorescence at 77 K in dichloromethane. The double-layer polymer light-emitting diodes using 6a as emitters and a blend of poly(9,9-dioctylfluorene) and 2-(4-tert-butyl)-phenyl-5-biphenyl-1,3,4-oxadiazole as host matrix exhibit best performance with the maximum external quantum efficiency as high as 8.6% at 0.66 mA cm(-2). (C) 2009 Elsevier Ltd. All rights reserved.