Origin of electrophosphorescence from a doped polymer light emitting diode
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 0.2 wt% PtOEP, Forster 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{close_quote}s is charge trapping followed by recombination on PtOEP molecules.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40203629
- Journal Information:
- Physical Review B, Vol. 63, Issue 23; Other Information: DOI: 10.1103/PhysRevB.63.235206; Othernumber: PRBMDO000063000023235206000001; 085120PRB; PBD: 15 Jun 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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