A Shift from Diffusion Assisted to Energy Transfer Controlled Fluorescence Quenching in Polymer-Fullerene Photovoltaic Blends

Alexander J. Ward, Arvydas Ruseckas, Ifor D. W. Samuel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

Singlet exciton diffusion and decay dynamics were investigated in two conjugated polymers: the high performance photovoltaic material, PCDTBT, and the substituted poly(p-phenylenevinylene), MEH-PPV, blended with fullerenes. Polymer fluorescence dynamics were measured on a planar quenching interface and in blends with varying concentrations of fullerene acceptor. At very low concentrations of filllerene, fluorescence quenching is assisted by exciton diffusion in the polymer, whereas direct Forster-type energy transfer to the fullerene is found to be the dominant mechanism at higher fullerene concentrations. The rate of quenching in the diffusion-assisted regime is found to be consistent with exciton diffusion coefficients calculated from the fluorescence quenching on a planar interface. The results also show that in unannealed films the onset of phase segregation occurs at concentrations of 4 wt % of C-61-PCBM in MEH-PPV and 7 wt % of C-71-PCBM in PCDTBT and that fullerenes remain dispersed as single molecules within polymer films below this concentration threshold.

Original languageEnglish
Pages (from-to)23931-23937
Number of pages7
JournalJournal of Physical Chemistry C
Volume116
Issue number45
DOIs
Publication statusPublished - 15 Nov 2012

Keywords

  • OPTIMIZATION
  • SOLAR-CELLS
  • EXCITON DIFFUSION
  • DISSOCIATION
  • MEH-PPV
  • EFFICIENCY
  • MORPHOLOGY
  • CHARGE GENERATION
  • LENGTH
  • ORGANIC SEMICONDUCTORS

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