Photoexcitation dynamics of coupled semiconducting carbon nanotube thin films

Randy D. Mehlenbacher, Meng Yin Wu, Maksim Grechko, Jennifer E. Laaser, Michael S. Arnold, Martin T. Zanni

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Carbon nanotubes are a promising means of capturing photons for use in solar cell devices. We time-resolved the photoexcitation dynamics of coupled, bandgap-selected, semiconducting carbon nanotubes in thin films tailored for photovoltaics. Using transient absorption spectroscopy and anisotropy measurements, we found that the photoexcitation evolves by two mechanisms with a fast and long-range component followed by a slow and short-range component. Within 300 fs of optical excitation, 20% of nanotubes transfer their photoexcitation over 5-10 nm into nearby nanotube fibers. After 3 ps, 70% of the photoexcitation resides on the smallest bandgap nanotubes. After this ultrafast process, the photoexcitation continues to transfer on a ∼10 ps time scale but to predominantly aligned tubes. Ultimately the photoexcitation hops twice on average between fibers. These results are important for understanding the flow of energy and charge in coupled nanotube materials and light-harvesting devices.

Original languageEnglish (US)
Pages (from-to)1495-1501
Number of pages7
JournalNano letters
Volume13
Issue number4
DOIs
StatePublished - Apr 10 2013

Keywords

  • Carbon nanotube
  • anisotropy
  • exciton
  • photovoltaic
  • transient absorption

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