Efficient pure blue electroluminescence from ter(9,9, 9″, 9″-bihexyl-9′, 9′-diphenyl)-fluorenes

Abstract

An oligomer of polyfluorene, ter(9,9, 9″, 9″ -bihexyl- 9′, 9′ -diphenyl)fluorenes (THPF), is used as a blue-emitting material to achieve efficient pure blue electroluminescence. Based on a 4, 4′, 4″ -tri (N -carbazolyl)-triphenylamine hole-transporting layer, a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline hole-blocking layer, an (8-hydroxyquinoline) aluminum electron-transporting layer, and a LiFAl cathode, the device has two emission peaks at 404 and 424 nm, chromaticity coordinates at (0.18, 0.09), and a maximum efficiency of 1.27 cdA. By using a submonolayer of 5,6,11,12-tetraphenylnaphthacene as a carrier detector, we demonstrate that THPF functions well as an electron-transporting layer, similar to Alq. © 2005 American Institute of Physics.