Photainduced Carrier Generation and Decay Dynamics in Intercalated and Non-intercalated Polymer

Fullerene Bulk Heterojunctions

William L. Rance, Andrew J. Ferguson, Thomas McCarthy-Ward, Martin Heeney, David S. Ginley, Dana C. Olson, Garry Rumbles, Nikos Kopidakis*

*Corresponding author for this work

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

The dependence of photoinduced carrier generation and decay on donor-acceptor nanomorphology is reported as a function of composition for blends of the polymer poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b] thiophene) (pBTTT-C14) with two electron-accepting fullerenes: phenyl-C71-butyric acid methyl ester (PC71BM) or the bisadduct of phenyl-C61-butyric acid methyl ester (bis-PC 61BM). The formation of partially or fully intercalated bimolecular crystals at weight ratios up to 1:1 for pBTTT-C14:PC71BM blends leads to efficient exciton quenching due to a combination of static and dynamic mechanisms. At higher fullerene loadings, pure PC71BM domains are formed that result in an enhanced free carrier lifetime, as a consequence of spatial separation of the electron and hole into different phases, and the dominant contribution to the photoconductance comes from the high-frequency electron mobility in the fullerene clusters. In the pBTTT-C14:bis- PC61BM system, phase separation results in a non-intercalated structure, independent of composition, which is characterized by exciton quenching that is dominated by a dynamic process, an enhanced carrier lifetime and a hole-dominated photoconductance signal. The results indicate that intercalation of fullerene into crystalline polymer domains is not detrimental to the density of long-lived carriers, suggesting that efficient organic photovoltaic devices could be fabricated that incorporate intercalated structures, provided that an additional pure fullerene phase is present for charge extraction.

Original languageEnglish
Pages (from-to)5635-5646
Number of pages12
JournalACS Nano
Volume5
Issue number7
DOIs
Publication statusPublished - 26 Jul 2011
Externally publishedYes

Keywords

  • blend
  • conjugated polymer
  • electron transfer
  • fullerene
  • intercalation
  • photoconductance

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    Rance, W. L., Ferguson, A. J., McCarthy-Ward, T., Heeney, M., Ginley, D. S., Olson, D. C., ... Kopidakis, N. (2011). Photainduced Carrier Generation and Decay Dynamics in Intercalated and Non-intercalated Polymer: Fullerene Bulk Heterojunctions. ACS Nano, 5(7), 5635-5646. https://doi.org/10.1021/nn201251v