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Solution-Processible Conjugated Electrophosphorescent Polymers

Title data

Sandee, Albertus J. ; Williams, Charlotte K. ; Evans, Nicholas R. ; Davies, John E. ; Boothby, Clare E. ; Köhler, Anna ; Friend, Richard H. ; Holmes, Andrew B.:
Solution-Processible Conjugated Electrophosphorescent Polymers.
In: Journal of the American Chemical Society. Vol. 126 (2004) Issue 22 . - pp. 7041-7048.
ISSN 1520-5126
DOI: https://doi.org/10.1021/ja039445o

Official URL: Volltext

Abstract in another language

We report the synthesis and photophysical study of a series of solution-processible phosphorescent iridium complexes. These comprise bis-cyclometalated iridium units [Ir(ppy)2(acac)] or [Ir(btp)2(acac)] where ppy is 2-phenylpyridinato, btp is 2-(2‘-benzo[b]thienyl)pyridinato, and acac is acetylacetonate. The iridium units are covalently attached to and in conjugation with oligo(9,9-dioctylfluorenyl-2,7-diyl) [(FO)n] to form complexes [Ir(ppy-(FO)n)2(acac)] or [Ir(btp-(FO)n)2(acac)], where the number of fluorene units, n, is 1, 2, 3, ∼10, ∼20, ∼30, or ∼40. All the complexes exhibit emission from a mixed triplet state in both photoluminescence and electroluminescence, with efficient quenching of the fluorene singlet emission. Short-chain complexes, 11−13, [Ir(ppy-(FO)n-FH)2(acac)] where n = 0, 1, or 2, show green light emission, red-shifted through the FO attachment by about 70 meV, but for longer chains there is quenching because of the lower energy triplet state associated with polyfluorene. In contrast, polymer complexes 18−21 [Ir(btp-(FO)n)2(acac)] where n is 5−40 have better triplet energy level matching and can be used to provide efficient red phosphorescent polymer light-emitting diodes, with a red shift due to the fluorene attachment of about 50 meV. We contrast this small (50−70 meV) and short-range modification of the triplet energies through extended conjugation, with the much more substantial evolution of the π−π* singlet transitions, which saturate at about n = 10. These covalently bound materials show improvements in efficiency over simple blends and will form the basis of future investigations into energy-transfer processes occurring in light-emitting diodes.

Further data

Item Type: Article in a journal
Refereed: No
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie - Univ.-Prof. Dr. Anna Köhler
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Lehrstuhl Experimentalphysik II - Optoelektronik weicher Materie
Result of work at the UBT: No
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 16 Mar 2015 14:06
Last Modified: 16 Mar 2015 14:06
URI: https://eref.uni-bayreuth.de/id/eprint/8331