Charge transfer excitons in bulk heterojunctions of a polyfluorene copolymer and a fullerene derivative

Maria Antonietta Loi*, Stefano Toffanin, Michele Muccini, Michael Forster, Ulrich Scherf, Markus Scharber

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

188 Citations (Scopus)
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Abstract

The photophysical properties of blends of fluorene copolymer and the fullerene derivative PCBM are analyzed with a particular attention to photovoltaic applications. The properties of the blends are determined by the relative alignment of the HOMO energy levels. In the blend where the HOMO levels of the copolymer and the fullerene are aligned there is not signature of charge stabilization and photovoltaic effect. While in the blend where there is an offset between the HOMO levels the charge stabilization is accompanied by good photovoltaic performances. The photoluminescence spectrum of the latter blend is characterized by the appearance of a new peak at low energy with a lifetime of a few ns that red-shifts with the increase of the PCBM percentage. The feature is attributed to the emission from a charge-transfer exciton that is red-shifted by the change of dielectric constant of the medium.

Original languageEnglish
Pages (from-to)2111-2116
Number of pages6
JournalAdvanced Functional Materials
Volume17
Issue number13
DOIs
Publication statusPublished - 3-Sep-2007

Keywords

  • SOLAR-CELL APPLICATIONS
  • THIN-FILMS
  • PERFORMANCE
  • BLENDS
  • METHANOFULLERENE
  • MORPHOLOGY
  • TRANSPORT
  • POLYMERS
  • MOBILITY
  • TIME

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