Poly(p-phenylenevinylene) light-emitting diodes: Enhanced electroluminescent efficiency through charge carrier confinement

A. R. Brown, D. D.C. Bradley, J. H. Burroughes, R. H. Friend, N. C. Greenham, P. L. Burn, A. B. Holmes, A. Kraft

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We have fabricated light-emitting diodes with poly(p-phenylenevinylene) as the emissive layer, and with an electron-transporting layer formed from a solid state dispersion of 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole in poly(methyl methacrylate), placed between this and the negative electrode. These structures show typically a tenfold improvement in efficiency in the low-voltage regime and an eightfold improvement in the high-voltage regime over devices without the electron-transporting layer. Typical efficiencies are about 0.8% photons/electron. We consider that the role of the electron-transport layer is to confine holes to the emissive layer.
Original languageEnglish (US)
JournalApplied Physics Letters
Issue number23
StatePublished - Dec 1 1992
Externally publishedYes

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