Enhanced Thermoelectric Performance of As-Grown Suspended Graphene Nanoribbons

Qin Yi Li, Tianli Feng, Wakana Okita, Yohei Komori, Hiroo Suzuki, Toshiaki Kato, Toshiro Kaneko, Tatsuya Ikuta, Xiulin Ruan, Koji Takahashi

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Conventionally, graphene is a poor thermoelectric material with a low figure of merit (ZT) of 10-4-10-3. Although nanostructuring was proposed to improve the thermoelectric performance of graphene, little experimental progress has been accomplished. Here, we carefully fabricated as-grown suspended graphene nanoribbons with quarter-micron length and â40 nm width. The ratio of electrical to thermal conductivity was enhanced by 1-2 orders of magnitude, and the Seebeck coefficient was several times larger than bulk graphene, which yielded record-high ZT values up to â0.1. Moreover, we observed a record-high electronic contribution of â20% to the total thermal conductivity in the nanoribbon. Concurrent phonon Boltzmann transport simulations reveal that the reduction of lattice thermal conductivity is mainly attributed to quasi-ballistic phonon transport. The record-high ratio of electrical to thermal conductivity was enabled by the disparate electron and phonon mean free paths as well as the clean samples, and the enhanced Seebeck coefficient was attributed to the band gap opening. Our work not only demonstrates that electron and phonon transport can be fundamentally tuned and decoupled in graphene but also indicates that graphene with appropriate nanostructures can be very promising thermoelectric materials.

Original languageEnglish
Pages (from-to)9182-9189
Number of pages8
JournalACS Nano
Volume13
Issue number8
DOIs
Publication statusPublished - Aug 27 2019
Externally publishedYes

Keywords

  • electrical conductivity
  • phonon transport
  • Seebeck coefficient
  • suspended graphene nanoribbon
  • thermoelectricity

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Fingerprint Dive into the research topics of 'Enhanced Thermoelectric Performance of As-Grown Suspended Graphene Nanoribbons'. Together they form a unique fingerprint.

Cite this