Size‐ and Temperature‐Dependent Suppression of Phonon Thermal Conductivity in Carbon Nanotube Thermoelectric Films

Devin Wesenberg, Michael Roos, Azure Avery, Jeffrey Blackburn, Andrew Ferguson, Barry Zink

Research output: Contribution to journalArticlepeer-review

13 Scopus Citations


Heat transport in nanoscale carbon materials such as carbon nanotubes and graphene is normally dominated by phonons. Here, measurements of in-plane thermal conductivity, electrical conductivity, and thermopower are presented from 77–350 K on two films with thickness <100 nm formed from semiconducting single-walled carbon nanotubes. These measurements are made with silicon–nitride membrane thermal isolation platforms. The two films, formed from disordered networks of tubes with differing tube and bundle size, have very different thermal conductivity. One film matches a simple model of heat conduction assuming constant phonon velocity and mean free path, and 3D Debye heat capacity with a Debye temperature of 770 K. The second film shows a more complicated temperature dependence, with a dramatic drop in a relatively narrow window near 200 K where phonon contributions to thermal conductivity essentially vanish. This causes a corresponding large increase in thermoelectric figure-of-merit at the same temperature. A better understanding of this behavior can allow significant improvement in thermoelectric efficiency of these low-cost earth-abundant, organic electronic materials. Heat and charge conductivity near room temperature is also presented as a function of doping, which provides further information on the interaction of dopant molecules and phonon transport in disordered nanotube films.

Original languageAmerican English
Article number2000746
Number of pages8
JournalAdvanced Electronic Materials
Issue number11
StatePublished - 2020

Bibliographical note

Publisher Copyright:
© 2020 Wiley-VCH GmbH

NREL Publication Number

  • NREL/JA-5900-77234


  • carbon nanotubes
  • organic thermoelectrics
  • thermal conductivity


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