Elucidating the Role of Molecule-Electrode Interfacial Defects in Charge Tunneling Characteristics of Large-Area Junctions

Gyu Don Kong, Junji Jin, Martin Thuo, Hyunsun Song, Joonyoung F. Joung, Sungnam Park, Hyo Jae Yoon

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)


Interfacial chemistry at organic-inorganic contact critically determines the function of a wide range of molecular and organic electronic devices and other systems. The chemistry is, however, difficult to understand due to the lack of easily accessible in-operando spectroscopic techniques that permit access to interfacial structure on a molecular scale. Herein, we compare two analogous junctions formed with identical organic thin film and different liquid top-contacts (water droplet vs eutectic gallium indium alloy) and elucidate the puzzling interfacial characteristics. Specifically, we fine-tune the surface topography of the organic surface using mixed self-assembled monolayers (SAMs): single component SAM composed of rectifier (2,2′-bipyridyl-terminated n-undecanethiolate; denoted as SC11BIPY) is systematically diluted with nonrectifying n-alkanethiolates of different lengths (denoted as SCn where n = 8, 10, 12, 14, 16, 18). Characterization of the resulting mixed SAMs in wettability and tunneling currents with the two separate liquid top-contacts allows us to investigate the role of phase segregation and gauche defect in the SAM//liquid interfaces. The results reported here show the difference in length between SC11BIPY and SCn is translated into nanoscopic pits and gauche-conformer defects on the surface, and the difference in contact force - hydrostatic vs user pressures - and hence conformity of contact account for the difference in wettability and rectification behaviors. Our work provides an insight into the role of molecule-electrode interfacial defects in performance of molecular-scale electronic devices.

Original languageEnglish
Pages (from-to)12303-12307
Number of pages5
JournalJournal of the American Chemical Society
Issue number38
Publication statusPublished - 2018 Sep 26

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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