Red-emitting electroluminescent devices based on osmium-complexes-doped blend of poly(vinylnaphthalene) and 1,3,4-oxadiazole derivative

Efficient red electrophosphorescence was achieved from double-layer light-emitting devices using osmium (Os)-complexes-doped blend of poly(vinylnaphthalene) (PVN) and 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PVN:PBD) as the emitting layer. Blending PVN with PBD greatly suppresses the electromer emission of PVN. The PVN:PBD blend emanates a short-wavelength electroluminescence emission peaking at around 375 nm, which overlaps well with the absorption spectra of the Os complexes and ensures very efficient energy transfer to the Os-complex dopants. The best external quantum efficiency of the double-layer devices was 2.2%, with a photometric efficiency of 1.9 cd/A.