title: Ultrafast Exciton Hopping Observed in Bare Semiconducting Carbon Nanotube Thin Films with Two-Dimensional White-Light Spectroscopy.
abstract: We observe ultrafast energy transfer between bare carbon nanotubes in a thin film using two-dimensional (2D) white-light spectroscopy. Using aqueous two-phase separation, semiconducting carbon nanotubes are purified from their metallic counterparts and condensed into a 10 nm thin film with no residual surfactant. Cross peak intensities put the time scale for energy transfer at <60 fs, and 2D anisotropy measurements determine that energy transfer is most efficient between parallel nanotubes, thus favoring directional energy flow. Lifetimes are about 300 fs. Thus, these results are in sharp contrast to thin films prepared from nanotubes that are wrapped by polymers, which exhibit picosecond energy transfer and randomize the direction of energy flow. Ultrafast energy flow and directionality are exciting properties for next-generation photovoltaics, photodetectors, and other devices.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53703, United States.
authors.forename: Randy D
authors.initials: RD
authors.lastname: Mehlenbacher
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison , 1509 University Avenue, Madison, Wisconsin 53706, United States.
authors.forename: Jialiang
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53703, United States.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Kearns
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison , 1509 University Avenue, Madison, Wisconsin 53706, United States.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Shea
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53703, United States.
authors.forename: Jessica T
authors.initials: JT
authors.lastname: Flach
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53703, United States.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: McDonough
authors.affiliation: Department of Electrical and Computer Engineering, University of Wisconsin-Madison , 1415 Engineering Drive, Madison, Wisconsin 53706, United States.
authors.forename: Meng-Yin
authors.initials: MY
authors.lastname: Wu
authors.affiliation: Department of Materials Science and Engineering, University of Wisconsin-Madison , 1509 University Avenue, Madison, Wisconsin 53706, United States.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Arnold
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison , 1101 University Avenue, Madison, Wisconsin 53703, United States.
authors.forename: Martin T
authors.initials: MT
authors.lastname: Zanni
mesh_terms: D008027:Light; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010316:Particle Size; D013057:Spectrum Analysis
chemical_list: D037742:Nanotubes, Carbon