Effects of the substituent position on the structural order, work function change, and thermopower of dichloro-substituted benzenethiolate self-assembled monolayers on Au(1 1 1)

Sicheon Seong, Hungu Kang, Haeri Kim, Young Ji Son, Jiung Jang, Shoichi Maeda, Shunta Chikami, Tomohiro Hayashi, Hyo Jae Yoon, Jaegeun Noh

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1 Citation (Scopus)

Abstract

The surface structures, electrochemical behaviors, work function changes, and thermopower of dichloro-substituted benzenethiolate self-assembled monolayers (SAMs) on gold surfaces prepared by vapor deposition were investigated using scanning tunneling microscopy (STM), cyclic voltammetry, Kelvin probe force microscopy, and thermoelectric junction measurements to understand the effects of their substituent positions. STM observations revealed that the adsorption of 2,4-dichlorobenzenethiol (2,4-DCBT) on Au(1 1 1) at 363 K for 1 h led to the formation of short-range ordered domains with a (5 × 6√7)R20° structure, while the SAMs formed at 363 K for 4 h consisted of long-range well-ordered domains with a (√3 × 5) structure. 3,4-Dichlorobenzenethiol (3,4-DCBT) SAMs showed coexistence of partial ordered domains and a disordered phase, while 3,4-DCBT SAMs showed fully disordered phases regardless of deposition time. Moreover, the Seebeck coefficient (S) increased in the order of 3,4-DCBT (4.6 ± 0.1 μV/K) < 2,4-DCBT (5.0 ± 0.4 μV/K) < 3,5-DCBT (5.2 ± 0.1 μV/K). Interestingly, the trend of S values was qualitatively consistent with that of the work function change (ΔΦ) of the SAMs. The reductive desorption behavior, work function shifts, and thermopower of aromatic thiolate SAMs were significantly modified by the structural order and direction of molecular dipoles of dichloro-substituted benzenethiols.

Original languageEnglish
Article number158661
JournalApplied Surface Science
Volume643
DOIs
Publication statusPublished - 2024 Jan 15

Bibliographical note

Publisher Copyright:
© 2023 Elsevier B.V.

Keywords

  • Dichlorobenzenethiols
  • Kelvin probe force microscopy
  • Scanning tunneling microscopy
  • Seebeck coefficient
  • Self-assembled monolayers
  • Surface structure

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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