TY - JOUR
T1 - Quantifying Molecular Structure-Tunneling Conductance Relationships
T2 - Oligophenylene Dimethanethiol vs Oligophenylene Dithiol Molecular Junctions
AU - Nguyen, Quyen Van
AU - Xie, Zuoti
AU - Daniel Frisbie, C.
N1 - Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.
PY - 2021/2/25
Y1 - 2021/2/25
N2 - We report quantitative analysis of tunneling conductance in molecular junctions based on self-Assembled monolayers (SAMs) of oligophenylene dimethanethiols (OPDMn) in which-CH2-spacers flank either side of the phenylene (n = 1), biphenylene (n = 2), and terphenylene (n = 3) aromatic cores. The current-voltage (I-V) characteristics for the OPDMn junctions with Au and Pt contacts are analyzed quantitatively with a previously validated single level model (SLM) to extract key junction metrics, namely the HOMO-To-Fermi-level offset, h, and the electronic coupling, . Independent determination of h by ultraviolet photoelectron spectroscopy (UPS) corroborates the estimation of h from the I-V characteristics and provides strong evidence for the validity of the SLM analysis. Further, comparison of the results for OPDMn junctions with those for oligophenylene dithiol (OPDn) junctions, which do not have-CH2-spacers, reveals that the much larger resistance for OPDMn (1000-fold) is primarily due to a 50-fold decrease in and not to any significant change in h; h is nearly identical for OPDMn and OPDn junctions for each value of n. Overall, our results provide a clear delineation of the influence of-CH2-spacers on h and and give further evidence that the analytical SLM is a useful tool for determining structure-Transport relationships in molecular tunnel junctions.
AB - We report quantitative analysis of tunneling conductance in molecular junctions based on self-Assembled monolayers (SAMs) of oligophenylene dimethanethiols (OPDMn) in which-CH2-spacers flank either side of the phenylene (n = 1), biphenylene (n = 2), and terphenylene (n = 3) aromatic cores. The current-voltage (I-V) characteristics for the OPDMn junctions with Au and Pt contacts are analyzed quantitatively with a previously validated single level model (SLM) to extract key junction metrics, namely the HOMO-To-Fermi-level offset, h, and the electronic coupling, . Independent determination of h by ultraviolet photoelectron spectroscopy (UPS) corroborates the estimation of h from the I-V characteristics and provides strong evidence for the validity of the SLM analysis. Further, comparison of the results for OPDMn junctions with those for oligophenylene dithiol (OPDn) junctions, which do not have-CH2-spacers, reveals that the much larger resistance for OPDMn (1000-fold) is primarily due to a 50-fold decrease in and not to any significant change in h; h is nearly identical for OPDMn and OPDn junctions for each value of n. Overall, our results provide a clear delineation of the influence of-CH2-spacers on h and and give further evidence that the analytical SLM is a useful tool for determining structure-Transport relationships in molecular tunnel junctions.
UR - http://www.scopus.com/inward/record.url?scp=85101532869&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.0c11514
DO - 10.1021/acs.jpcc.0c11514
M3 - 文章
AN - SCOPUS:85101532869
SN - 1932-7447
VL - 125
SP - 4292
EP - 4298
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 7
ER -