Triplet level-dependent photoluminescence and photoconduction properties of π-conjugated polymer thin films doped by iridium complexes

Jongdeok An, Jungyun Chang, Jungwook Han, Chan Im, Young Jun Yu, Dong Hoon Choi, Jung Il Jin, Tetsuro Majima

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Abstract

Triplet energy level-dependent decay pathways of excitons populated on iridium (Ir) complexes within π-conjugated polymeric matrices were studied by means of photoluminescence (PL) and photoconduction action spectroscopy. We chose a set of matrices, poly(9-vinylcarbazole) (PVK), poly[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl] (PF2/6), poly [2-(5′-cyano-5′-methyl-hexyloxy)-1,4-phenylene] (CNPPP), and poly [2-(5′-cyano-5′-methyl-hexyloxy)-1,4-phenylene-co-pridine] (CNPPP-py10 and CNPPP-Py20), having triplet energy levels ranging from 2.2 up to 3.0 eV. As Ir-complex dopants, we selected three phosphorescent emitters, iridium(III)bis(2-(2′-benzothienyl) pyridinato-N-acetylacetonate) (Ir(btp)2acac), iridium(III)fac-tris(2-phenylpyridine) (Ir(ppy)3), and iridium(III)bis[(4,6-fluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic), having triplet energy levels of 2.1, 2.5, and 2.7 eV, respectively. It was found that the triplet emission from the dopants, being populated via energy transfer from the matrices, was strongly dependent on the matching of triplet energy levels between matrix polymers and Ir-complexes. Photocurrent action spectra confirm effective exciton confinement at the dopants sites in the case of PVK matrix systems.

Original languageEnglish
Pages (from-to)371-376
Number of pages6
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume200
Issue number2-3
DOIs
Publication statusPublished - 2008 Dec 15

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Keywords

  • π-Conjugated polymer
  • Energy transfer
  • OLED
  • Phosphorescence
  • Photoluminescence

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)

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