Enhanced Thermopower of Saturated Molecules by Noncovalent Anchor-Induced Electron Doping of Single-Layer Graphene Electrode

Sohyun Park, Hwa Rang Kim, Juhee Kim, Byung Hee Hong, Hyo Jae Yoon

Research output: Contribution to journalArticlepeer-review

Abstract

Enhancing thermopower is a key goal in organic and molecular thermoelectrics. Herein, it is shown that introducing noncovalent contact with a single-layer graphene (SLG) electrode improves the thermopower of saturated molecules as compared to the traditional gold–thiolate covalent contact. Thermoelectric junction measurements with a liquid-metal technique reveal that the value of Seebeck coefficient in large-area junctions based on n-alkylamine self-assembled monolayers (SAMs) on SLG is increased up to fivefold compared to the analogous junction based on n-alkanethiolate SAMs on gold. Experiments with Raman spectroscopy and field-effect transistor analysis indicate that such enhancements benefit from the creation of new in-gap states and electron doping through noncovalent interaction between the amine anchor and the SLG electrode, which leads to a reduced energy offset between the Fermi level and the transport channel. This work demonstrates that control of interfacial bonding nature in molecular junctions improves the Seebeck effect in saturated molecules.

Original languageEnglish
Article number2103177
JournalAdvanced Materials
Volume33
Issue number41
DOIs
Publication statusPublished - 2021 Oct 14

Keywords

  • EGaIn
  • graphene
  • molecular thermoelectrics
  • Seebeck effect
  • self-assembled monolayers

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint

Dive into the research topics of 'Enhanced Thermopower of Saturated Molecules by Noncovalent Anchor-Induced Electron Doping of Single-Layer Graphene Electrode'. Together they form a unique fingerprint.

Cite this