Abstract
Molecular conformation, intermolecular interaction, and electrode-molecule contacts greatly affect charge transport in molecular junctions and interfacial properties of organic devices by controlling the molecular orbital alignment. Here, we statistically investigated the charge transport in molecular junctions containing self-assembled oligophenylene molecules sandwiched between an Au probe tip and graphene according to various tip-loading forces (FL) that can control the molecular-tilt configuration and the van der Waals (vdW) interactions. In particular, the molecular junctions exhibited two distinct transport regimes according to the FL dependence (i.e., FL-dependent and FL-independent tunneling regimes). In addition, the charge-injection tunneling barriers at the junction interfaces are differently changed when the FL ≤ 20 nN. These features are associated to the correlation effects between the asymmetry-coupling factor (η), the molecular-tilt angle (θ), and the repulsive intermolecular vdW force (FvdW) on the molecular-tunneling barriers. A more-comprehensive understanding of these charge transport properties was thoroughly developed based on the density functional theory calculations in consideration of the molecular-tilt configuration and the repulsive vdW force between molecules.
Original language | English |
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Pages (from-to) | 4322-4330 |
Number of pages | 9 |
Journal | Nano Letters |
Volume | 18 |
Issue number | 7 |
DOIs | |
Publication status | Published - 2018 Jul 11 |
Bibliographical note
Funding Information:This work was accomplished with financial support from the National Research Foundation of Korea grant nos. 2017R1D1A1B03035441, 2016R1A2B4009037, 2016R1C1B2007330, and 2017R1A5A1014862 (SRC Program: vdWMRC Center), the National Creative Research Laboratory Program (grant no. 2012026372), the KU-KIST research fund, and the Korea University Future Research Grant. In particular, we appreciate Prof. Taekyeong Kim for discussion and comments on our results.
Publisher Copyright:
© 2018 American Chemical Society.
Keywords
- Molecular junction
- graphene
- intermolecular van der Waals interaction
- molecular-tilt configuration
- transition voltage
ASJC Scopus subject areas
- Bioengineering
- General Chemistry
- General Materials Science
- Condensed Matter Physics
- Mechanical Engineering