Origin of electrophosphorescence from a doped polymer light emitting diode

P. A. Lane, L. C. Palilis, D. F. O’Brien, C. Giebeler, A. J. Cadby, D. G. Lidzey, A. J. Campbell, W. Blau, and D. D. C. Bradley
Phys. Rev. B 63, 235206 – Published 31 May 2001
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Abstract

The origin of electrophosphorescence from a doped polymer light emitting diode (LED) has been investigated. A luminescent polymer host, poly(9,9-dioctylfluorene) (PFO), was doped with a red phosphorescent dye, 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrin platinum(II) (PtOEP). The maximum external quantum efficiency of 3.5% was obtained at a concentration of 4% PtOEP by weight. Energy transfer mechanisms between PFO and PtOEP were studied by absorption, photoluminescence, and photoinduced absorption spectroscopy. Even though electroluminescence spectra were dominated by PtOEP at a concentration of only 0.2wt% PtOEP, Förster transfer of singlet excitons was weak and there was no evidence for Dexter transfer of triplet excitons. We conclude that the dominant emission mechanism in doped LED’s is charge trapping followed by recombination on PtOEP molecules.

  • Received 26 July 2000

DOI:https://doi.org/10.1103/PhysRevB.63.235206

©2001 American Physical Society

Authors & Affiliations

P. A. Lane1,*, L. C. Palilis1, D. F. O’Brien2, C. Giebeler1, A. J. Cadby1,†, D. G. Lidzey1, A. J. Campbell1,†, W. Blau2, and D. D. C. Bradley1,†

  • 1Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom
  • 2Physics Department, Trinity College, Dublin, Ireland

  • *Present address: C. S. Draper Laboratory, 555 Technology Square, Cambridge, MA 02139.
  • Present address: Blackett Laboratory, Imperial College, Prince Consort Road, London SW7 2BW, United Kingdom.

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Vol. 63, Iss. 23 — 15 June 2001

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