Abstract

Thermoelectric power generation, allowing recovery of part of the energy wasted as heat, is emerging as an important component of renewable energy and energy efficiency portfolios. Although inorganic semiconductors have traditionally been employed in thermoelectric applications, organic semiconductors garner increasing attention as versatile thermoelectric materials. Here we present a combined theoretical and experimental study suggesting that semiconducting single-walled carbon nanotubes with carefully controlled chirality distribution and carrier density are capable of large thermoelectric power factors, higher than 340 μW m−1 K−2, comparable to the best-performing conducting polymers and larger than previously observed for carbon nanotube films. Furthermore, we demonstrate that phonons are the dominant source of thermal conductivity in the networks, and that our carrier doping process significantly reduces the thermal conductivity relative to undoped networks. These findings provide the scientific underpinning for improved functional organic thermoelectric composites with carbon nanotube inclusions.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

     & Complex thermoelectric materials. Nature Mater. 7, 105–114 (2008).

  2. 2.

    , ,  & Bulk nanostructured thermoelectric materials: current research and future prospects. Energy Environ. Sci. 2, 466–479 (2009).

  3. 3.

    , ,  & Recent advances in thermoelectric nanocomposites. Nano Energy 1, 42–56 (2012).

  4. 4.

    et al. Power factor enhancement in solution-processed organic n-type thermoelectrics through molecular design. Adv. Mater. 26, 3473–3477 (2014).

  5. 5.

    , ,  & Impact of the doping method on conductivity and thermopower in semiconducting polythiophenes. Adv. Energy Mater. 5, 1401072 (2015).

  6. 6.

    , ,  & Engineered doping of organic semiconductors for enhanced thermoelectric efficiency. Nature Mater. 12, 719–723 (2013).

  7. 7.

    et al. Thermal conductivity and elastic constants of PEDOT:PSS with high electrical conductivity. Macromolecules 48, 585–591 (2015).

  8. 8.

    et al. Significant electronic thermal transport in the conducting polymer poly(3,4-ethylenedioxythiophene). Adv. Mater. 27, 2101–2106 (2015).

  9. 9.

    et al. Recent developments in the photophysics of single-walled carbon nanotubes for their use as active and passive material elements in thin film photovoltaics. Phys. Chem. Chem. Phys. 15, 14896–14918 (2013).

  10. 10.

    et al. Enhanced hole extraction in perovskite solar cells through carbon nanotubes. J. Phys. Chem. Lett. 5, 4207–4212 (2014).

  11. 11.

    et al. Precision printing and optical modeling of ultrathin SWCNT/C60 heterojunction solar cells. Nanoscale 7, 6556–6566 (2015).

  12. 12.

    et al. Photothermoelectric p–n junction photodetector with intrinsic broadband polarimetry based on macroscopic carbon nanotube films. ACS Nano 7, 7271–7277 (2013).

  13. 13.

    et al. Polyfluorene-sorted, carbon nanotube array field-effect transistors with increased current density and high on/off ratio. ACS Nano 8, 11614–11621 (2014).

  14. 14.

    et al. Systematic conversion of single walled carbon nanotubes into n-type thermoelectric materials by molecular dopants. Sci. Rep. 3, 3344 (2013).

  15. 15.

    et al. Varying the ionic functionalities of conjugated polyelectrolytes leads to both p- and n-type carbon nanotube composites for flexible thermoelectrics. Energy Environ. Sci. 8, 2341–2346 (2015).

  16. 16.

    , ,  & DNA sequence motifs for structure-specific recognition and separation of carbon nanotubes. Nature 460, 250–253 (2009).

  17. 17.

    , , ,  & Sorting carbon nanotubes by electronic structure using density differentiation. Nature Nanotech. 1, 60–65 (2006).

  18. 18.

    et al. Transparent conductive single-walled carbon nanotube networks with precisely tunable ratios of semiconducting and metallic nanotubes. ACS Nano 2, 1266–1274 (2008).

  19. 19.

    , ,  & Highly selective dispersion of single-walled carbon nanotubes using aromatic polymers. Nature Nanotech. 2, 640–646 (2007).

  20. 20.

    ,  & High-yield dispersions of large-diameter semiconducting single-walled carbon nanotubes with tunable narrow chirality distributions. ACS Nano 7, 2231–2239 (2013).

  21. 21.

    et al. Isolation of >1 nm diameter single-wall carbon nanotube species using aqueous two-phase extraction. ACS Nano 9, 5377–5390 (2015).

  22. 22.

    , ,  & Light-weight flexible carbon nanotube based organic composites with large thermoelectric power factors. ACS Nano 5, 7885–7892 (2011).

  23. 23.

    et al. Multilayered carbon nanotube/polymer composite based thermoelectric fabrics. Nano Lett. 12, 1307–1310 (2012).

  24. 24.

    et al. Completely organic multilayer thin film with thermoelectric power factor rivaling inorganic tellurides. Adv. Mater. 27, 2996–3001 (2015).

  25. 25.

    et al. Giant Seebeck coefficient in semiconducting single-wall carbon nanotube film. Appl. Phys. Express 7, 025103 (2014).

  26. 26.

    et al. Effect of inter-tube junctions on the thermoelectric power of mono-dispersed single walled carbon nanotube networks. J. Phys. Chem. C 118, 26454–26461 (2014).

  27. 27.

    , , ,  & Thermal conductance and thermopower of an individual single-wall carbon nanotube. Nano Lett. 5, 1842–1846 (2005).

  28. 28.

    , , ,  & Thermal conductance of an individual single-wall carbon nanotube above room temperature. Nano Lett. 6, 96–100 (2006).

  29. 29.

    , ,  & Thermal conductivity of single-walled carbon nanotubes. Phys. Rev. B 59, R2514–R2516 (1999).

  30. 30.

    et al. Turning carbon nanotubes from exceptional heat conductors into insulators. Phys. Rev. Lett. 102, 105901 (2009).

  31. 31.

     & Observation of Anderson localization in an electron gas. Phys. Rev. 181, 1336–1340 (1969).

  32. 32.

    ,  & Thermoelectric and magnetothermoelectric transport measurements of graphene. Phys. Rev. Lett. 102, 096807 (2009).

  33. 33.

    , ,  & Ultrafast spectroscopic signature of charge transfer between single-walled carbon nanotubes and C60. ACS Nano 8, 8573–8581 (2014).

  34. 34.

    , , ,  & Stable charge-transfer doping of transparent single-walled carbon nanotube films. Chem. Mater. 22, 5179–5183 (2010).

  35. 35.

    et al. Ultrasmooth, large-area, high-uniformity, conductive transparent single-walled-carbon-nanotube films for photovoltaics produced by ultrasonic spraying. Adv. Mater. 21, 3210–3216 (2009).

  36. 36.

    et al. n-type transparent conducting films of small molecule and polymer amine doped single-walled carbon nanotubes. ACS Nano 5, 3714–3723 (2011).

  37. 37.

    , ,  & Role of dopants in long-range charge carrier transport for p-type and n-type graphene transparent conducting thin films. ACS Nano 7, 7251–7261 (2013).

  38. 38.

     & Dependence of optical transition energies on structure for single-walled carbon nanotubes in aqueous suspension: an empirical Kataura plot. Nano Lett. 3, 1235–1238 (2003).

  39. 39.

    , ,  & Excitons in carbon nanotubes: diameter and chirality trends. Phys. Status Solidi b 244, 4016–4020 (2007).

  40. 40.

    et al. Optimization of the thermoelectric figure of merit in the conducting polymer poly(3,4-ethylenedioxythiophene). Nature Mater. 10, 429–433 (2011).

  41. 41.

    et al. Semi-metallic polymers. Nature Mater. 13, 190–194 (2013).

  42. 42.

    , ,  & Thermal conductivity of micromachined low-stress silicon-nitride beams from 77 to 325 K. J. Appl. Phys. 105, 043501 (2009).

  43. 43.

    , , ,  & Thermal and electrical conductivity of approximately 100-nm permalloy, Ni, Co, Al, and Cu films and examination of the Wiedemann–Franz Law. Phys. Rev. B 92, 214410 (2015).

  44. 44.

    et al. A simple and complete purification of single-walled carbon nanotube materials. Adv. Mater. 11, 1354–1358 (1999).

  45. 45.

    Projector augmented-wave method. Phys. Rev. B 50, 17953–17979 (1994).

  46. 46.

    ,  & Generalized gradient approximation made simple. Phys. Rev. Lett. 77, 3865–3868 (1996).

  47. 47.

     & From ultrasoft pseudopotentials to the projector augmented-wave method. Phys. Rev. B 59, 1758–1775 (1999).

  48. 48.

     & Surfactant-assisted growth of CdS thin films for photovoltaic applications. J. Vac. Sci. Technol. A 24, 497–504 (2006).

  49. 49.

    ,  & Density-of-states effective mass and scattering parameter measurements by transport phenomena in thin films. Rev. Sci. Instrum. 71, 462–466 (2000).

  50. 50.

     & Correcting for contact geometry in Seebeck coefficient measurements of thin film devices. Org. Electron. 15, 2250–2255 (2014).

  51. 51.

    et al. Heat transport by long mean free path vibrations in amorphous silicon nitride near room temperature. Phys. Rev. B 87, 214305 (2013).

Download references

Acknowledgements

The investigation of the thermoelectric properties of the SWCNT networks carried out by the NREL authors was performed under a grant from the Laboratory Directed Research and Development Program at the National Renewable Energy Laboratory (NREL). The development of the s-SWCNT separations at NREL was funded by the Solar Photochemistry Program, Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, US Department of Energy (DOE). NREL is supported by the US Department of Energy under Contract No. DE-AC36-08GO28308. E.M.M. would like to thank the National Renewable Energy Laboratory Director’s Fellowship for funding. B.H.Z. and S.L.G. would like to thank the Department of Energy, Office of Science, Science Undergraduate Laboratory Internship (SULI) Program for funding. Work at KAIST was supported by the National Research Foundation of Korea (2015R1A2A2A05027766) and Global Frontier R&D (2011-0031566: Center for Multiscale Energy Systems) programmes. Work at D.U. is supported by NSF-DMR (DMR-0847796 and DMR-1410247). This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52-06NA25396) and Sandia National Laboratories (Contract DE-AC04-94AL85000).

Author information

Author notes

    • Sarah L. Guillot

    Present address: Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.

Affiliations

  1. Chemistry and Nanoscience Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA

    • Azure D. Avery
    • , Ben H. Zhou
    • , Elisa M. Miller
    • , Rachelle Ihly
    • , Kevin S. Mistry
    • , Sarah L. Guillot
    • , Jeffrey L. Blackburn
    •  & Andrew J. Ferguson
  2. Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Republic of Korea

    • Jounghee Lee
    • , Eui-Sup Lee
    •  & Yong-Hyun Kim
  3. Department of Physics and Astronomy, University of Denver, Denver, Colorado 80208, USA

    • Devin Wesenberg
    •  & Barry L. Zink

Authors

  1. Search for Azure D. Avery in:

  2. Search for Ben H. Zhou in:

  3. Search for Jounghee Lee in:

  4. Search for Eui-Sup Lee in:

  5. Search for Elisa M. Miller in:

  6. Search for Rachelle Ihly in:

  7. Search for Devin Wesenberg in:

  8. Search for Kevin S. Mistry in:

  9. Search for Sarah L. Guillot in:

  10. Search for Barry L. Zink in:

  11. Search for Yong-Hyun Kim in:

  12. Search for Jeffrey L. Blackburn in:

  13. Search for Andrew J. Ferguson in:

Contributions

A.D.A., B.H.Z., R.I., K.S.M. and S.L.G. fabricated various polymer:s-SWCNT thin films. A.D.A., B.H.Z., J.L.B. and A.J.F. characterized the thermoelectric and optical properties of polymer:s-SWCNT thin films. J.L., E.-S.L. and Y.-H.K. conducted the theoretical calculations. E.M.M. conducted the photoelectron spectroscopy characterization. D.W. and B.L.Z. conducted the thermal conductivity measurements and some electrical conductivity measurements. A.D.A. and R.I. measured film thickness using atomic force microscopy. A.D.A., B.L.Z., Y.-H.K., J.L.B. and A.J.F. provided theoretical insight, data interpretation and project direction. A.D.A., J.L., E.-S.L., E.M.M., B.L.Z., Y.-H.K., J.L.B. and A.J.F. were involved in the redaction of the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Jeffrey L. Blackburn or Andrew J. Ferguson.

Supplementary information

PDF files

  1. 1.

    Supplementary Information

    Supplementary Methods, Supplementary Notes 19, Supplementary Figures 1–10, Supplementary Table 1, Supplementary References.

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nenergy.2016.33