Charge separation in P3HT

SWCNT blends studied by EPR: Spin signature of the photoinduced charged state in SWCNT

Jens Niklas, Josh M. Holt, Kevin Mistry, Gary Rumbles, Jeffrey L. Blackburn, Oleg G. Poluektov

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Single-wall carbon nanotubes (SWCNTs) could be employed in organic photovoltaic (OPV) devices as a replacement or additive for currently used fullerene derivatives, but significant research remains to explain fundamental aspects of charge generation. Electron paramagnetic resonance (EPR) spectroscopy, which is sensitive only to unpaired electrons, was applied to explore charge separation in P3HT:SWCNT blends. The EPR signal of the P3HT positive polaron increases as the concentration of SWCNT acceptors in a photoexcited P3HT:SWCNT blend is increased, demonstrating long-lived charge separation induced by electron transfer from P3HT to SWCNTs. An EPR signal from reduced SWCNTs was not identified in blends due to the free and fast-relaxing nature of unpaired SWCNT electrons as well as spectral overlap of this EPR signal with the signal from positive P3HT polarons. However, a weak EPR signal was observed in chemically reduced SWNTs, and the g values of this signal are close to those of C70-PCBM anion radical. The anisotropic line shape indicates that these unpaired electrons are not free but instead localized.

Original languageEnglish
Pages (from-to)601-606
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume5
Issue number3
DOIs
Publication statusPublished - Feb 6 2014

Fingerprint

Carbon Nanotubes
polarization (charge separation)
Paramagnetic resonance
Carbon nanotubes
electron paramagnetic resonance
carbon nanotubes
signatures
Electrons
Fullerenes
Gene Conversion
Polarons
electrons
polarons
fullerenes
Anions
line shape
electron transfer
Negative ions
Spectroscopy
anions

Keywords

  • bulk heterojunctions
  • electron paramagnetic resonance
  • fullerene
  • organic photovoltaic
  • polymer
  • radical anion
  • radical cation
  • single-wall carbon nanotubes

ASJC Scopus subject areas

  • Materials Science(all)

Cite this

Charge separation in P3HT : SWCNT blends studied by EPR: Spin signature of the photoinduced charged state in SWCNT. / Niklas, Jens; Holt, Josh M.; Mistry, Kevin; Rumbles, Gary; Blackburn, Jeffrey L.; Poluektov, Oleg G.

In: Journal of Physical Chemistry Letters, Vol. 5, No. 3, 06.02.2014, p. 601-606.

Research output: Contribution to journalArticle

Niklas, Jens ; Holt, Josh M. ; Mistry, Kevin ; Rumbles, Gary ; Blackburn, Jeffrey L. ; Poluektov, Oleg G. / Charge separation in P3HT : SWCNT blends studied by EPR: Spin signature of the photoinduced charged state in SWCNT. In: Journal of Physical Chemistry Letters. 2014 ; Vol. 5, No. 3. pp. 601-606.
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