Mechanically and Electrically Robust Self-Assembled Monolayers for Large-Area Tunneling Junctions

Yanxi Zhang, Xinkai Qiu, Pavlo Gordiichuk, Saurabh Soni, Theodorus L. Krijger, Andreas Herrmann, Ryan C. Chiechi*

*Bijbehorende auteur voor dit werk

OnderzoeksoutputAcademicpeer review

18 Citaten (Scopus)
243 Downloads (Pure)

Samenvatting

This paper examines the relationship between mechanical deformation and the electronic properties of self assembled monolayers (SAMs) of the oligothiophene 4-([2,2':5',2":5",2"'-quaterthiophen]-5-y1)butane-1-thiol (T4C4) in tunneling junctions using conductive probe atomic force microscopy (CP-AFM) and eutectic Ga-In (EGaIn). We compared shifts in conductivity, transition voltages, of T4C4 with increasing AFM tip loading force to alkanethiolates. While these shifts result from an increasing tilt angle from penetration of the SAM by the AFM tip for the latter, we ascribe them to distortions of the pi system present in T4C4, which is more mechanically robust than alkanethiolates of comparable length; SAMs comprising T4C4 shows about five times higher Young's modulus than alkanethiolates. Density functional theory calculations confirm that mechanical deformations shift the barrier height due to changes in the frontier orbitals caused by small rearrangements to the conformation of the quaterthiophene moiety. The mechanical robustness of T4C4 manifests as an increased tolerance to high bias in large-area EGaIn junctions suggesting that electrostatic pressure plays a significant role in the shorting of molecular junctions at high bias.

Originele taal-2English
Pagina's (van-tot)14920-14928
Aantal pagina's9
TijdschriftThe Journal of Physical Chemistry. C: Nanomaterials and Interfaces
Volume121
Nummer van het tijdschrift27
DOI's
StatusPublished - 13-jul-2017

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