Single-molecule electroluminescence and photoluminescence of polyfluorene unveils the photophysics behind the green emission band

Yoshihiro Honmou, Shuzo Hirata, Hideaki Komiyama, Junya Hiyoshi, Susumu Kawauchi, Tomokazu Iyoda, Martin Vacha

Research output: Contribution to journalArticlepeer-review

49 Scopus citations

Abstract

Optoelectronic properties of polyfluorene, a blue light-emitting organic semiconductor, are often degraded by the presence of green emission that originates mainly from oxidation of the polymer. Here, we use single-molecule electroluminescence (EL) and photoluminescence (PL) spectroscopy on polyfluorene chains confined in vertical cylinders of a phase-separated block copolymer to spectrally resolve the green band and investigate in detail the photophysical processes responsible for its appearance. In both EL and PL, a substantial fraction of polyfluorene chains shows spectrally stable green emission which is ascribed to a keto defect. In addition, in EL, we observe a new type of vibrationally resolved spectra distributed over a wide range of frequencies and showing strong spectral dynamics. Based on quantum chemical calculations, this type is proposed to originate from charge-assisted formation and stabilization of ground-state aggregates. The results are expected to have broad implications in the fields of photophysics and material design of polyfluorene materials. © 2014 Macmillan Publishers Limited. All rights reserved.
Original languageEnglish (US)
JournalNATURE COMMUNICATIONS
Volume5
Issue number1
DOIs
StatePublished - 2014
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)
  • Physics and Astronomy(all)

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