title: Enlightening the ultrahigh electrical conductivities of doped double-wall carbon nanotube fibers by Raman spectroscopy and first-principles calculations.
abstract: Highly aligned, packed, and doped carbon nanotube (CNT) fibers with electrical conductivities approaching that of copper have recently become available. These fibers are promising for high-power electrical applications that require light-weight, high current-carrying capacity cables. However, a microscopic understanding of how doping affects the electrical conductance of such CNT fibers in a quantitative manner has been lacking. Here, we performed Raman spectroscopy measurements combined with first-principles calculations to determine the position of the average Fermi energy and to obtain the temperature of chlorosulfonic-acid-doped double-wall CNT fibers under high current. Due to the unique way in which double-wall CNT Raman spectra depend on doping, it is possible to use Raman data to determine the doping level quantitatively. The correspondence between the Fermi level shift and the carbon charge transfer is derived from a tight-binding model and validated by several calculations. For the doped fiber, we were able to associate an average Fermi energy shift of ∼-0.7 eV with a conductance increase by a factor of ∼5. Furthermore, since current induces heating, local temperature determination is possible. Through the Stokes-to-anti-Stokes intensity ratio of the G-band peaks, we estimated a temperature rise at the fiber surface of ∼135 K at a current density of 2.27 × 108A m-2identical to that from the G-band shift, suggesting that thermalization between CNTs is well achieved.
authors.affiliation: CEMES-CNRS, UPR-8011, Université Fédérale de Toulouse-Midi-Pyrénées, 29 rue Jeanne Marvig, BP 94347 Toulouse, Cedex 4, France. pascal.puech@cemes.fr and LPCNO, UMR-5215 CNRS, INSA, Université Fédérale de Toulouse-Midi-Pyrénées, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Tristant
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Zubair
authors.affiliation: CEMES-CNRS, UPR-8011, Université Fédérale de Toulouse-Midi-Pyrénées, 29 rue Jeanne Marvig, BP 94347 Toulouse, Cedex 4, France. pascal.puech@cemes.fr.
authors.forename: Pascal
authors.initials: P
authors.lastname: Puech
authors.affiliation: CEMES-CNRS, UPR-8011, Université Fédérale de Toulouse-Midi-Pyrénées, 29 rue Jeanne Marvig, BP 94347 Toulouse, Cedex 4, France. pascal.puech@cemes.fr.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Neumayer
authors.affiliation: CEMES-CNRS, UPR-8011, Université Fédérale de Toulouse-Midi-Pyrénées, 29 rue Jeanne Marvig, BP 94347 Toulouse, Cedex 4, France. pascal.puech@cemes.fr.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Moyano
authors.affiliation: Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Chemistry, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Materials Science and NanoEngineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Headrick
authors.affiliation: Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Chemistry, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Materials Science and NanoEngineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
authors.forename: Dmitri E
authors.initials: DE
authors.lastname: Tsentalovich
authors.affiliation: Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Chemistry, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Materials Science and NanoEngineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
authors.forename: Colin C
authors.initials: CC
authors.lastname: Young
authors.affiliation: LPCNO, UMR-5215 CNRS, INSA, Université Fédérale de Toulouse-Midi-Pyrénées, Université de Toulouse, 135 Avenue de Rangueil, 31077 Toulouse, France.
authors.forename: Iann C
authors.initials: IC
authors.lastname: Gerber
authors.affiliation: Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Chemistry, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Materials Science and NanoEngineering, Rice University, 6100 Main St., Houston, Texas 77005, USA.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pasquali
authors.affiliation: Department of Electrical and Computer Engineering, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Materials Science and NanoEngineering, Rice University, 6100 Main St., Houston, Texas 77005, USA and Department of Physics and Astronomy, Rice University, 6100 Main St., Houston, Texas 77005, USA.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Kono
authors.affiliation: LNCMI-CNRS, UPR 3228, Université Fédérale de Toulouse-Midi-Pyrénées, 143 avenue de Rangueil, 31400 Toulouse, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Leotin