Origin of electrophosphorescence from a doped polymer light emitting diode- art. no. 235206

Citation
Pa. Lane et al., Origin of electrophosphorescence from a doped polymer light emitting diode- art. no. 235206, PHYS REV B, 6323(23), 2001, pp. 5206
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science
Journal title
PHYSICAL REVIEW B
ISSN journal
0163-1829 → ACNP
Volume
6323
Issue
23
Year of publication
2001
Database
ISI
SICI code
0163-1829(20010615)6323:23<5206:OOEFAD>2.0.ZU;2-8
Abstract
The origin of electrophosphorescence from a doped polymer light emitting di ode (LED) has been investigated. A luminescent polymer host, poly(9,9-dioct ylfluorene) (PFO), was doped with a red phosphorescent dye, 2,3,7,8,12,13,1 7,18-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 ab sorption, photoluminescence, and photoinduced absorption spectroscopy. Even though electroluminescence spectra were dominated by PtOEP at a concentrat ion of only 0.2 wt % PtOEP, Forster transfer of singlet excitons was weak a nd there was no evidence for Dexter transfer of tripler excitons. We conclu de that the dominant emission mechanism in doped LED's is charge trapping f ollowed by recombination on PtOEP molecules.