Specific issues related to the law of corresponding states for the charge transport in molecular junctions based on graphene electrodes

Bâldea, Ioan

doi:10.1016/j.apsusc.2018.02.149

Cited by 3 publications

(2 citation statements)

References 53 publications

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“…For symmetric junctions where off-resonant, single-step tunneling dominates, the analytical single level model (SLM) derived from the Landauer picture has proven to be a convenient theoretical tool to determine key transport parameters from junction current–voltage ( I–V ) characteristics. − ,,,,, These parameters include the HOMO (or LUMO) energy offset, ε h (or ε l ), and the orbital coupling Γ, as shown in Figure B. Recent work by Baldea − and the authors − ,− ,, has demonstrated that ε h and Γ are easily extracted from experimental data using the analytical SLM, and the resulting I–V prediction by SLM matches the experimental I–V characteristics very well. The validity of the SLM for simple tunnel junctions is also corroborated by independent determination of ε h by ultraviolet photoelectron spectroscopy (UPS) for oligophenylene thiol and alkanethiol systems, , and by its prediction of “universal” behavior for single-step tunneling that matches experimental findings. ,, …”

Section: Introductionmentioning

confidence: 99%

Quantifying Molecular Structure-Tunneling Conductance Relationships: Oligophenylene Dimethanethiol vs Oligophenylene Dithiol Molecular Junctions

2021

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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, εh, and the electronic coupling, Γ. Independent determination of εh by ultraviolet photoelectron spectroscopy (UPS) corroborates the estimation of εh 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 Γ and not to any significant change in εh; εh 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 εh and Γ and give further evidence that the analytical SLM is a useful tool for determining structure-transport relationships in molecular tunnel junctions.

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Section: Introductionmentioning

confidence: 99%

Quantifying Molecular Structure-Tunneling Conductance Relationships: Oligophenylene Dimethanethiol vs Oligophenylene Dithiol Molecular Junctions

2021

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“…It can be effectively used to extract and determine key transport parameters from I−V characteristics, including the HOMO (or LUMO) energy offset ε h (or ε l ) with respect to the electrode Fermi energy level and coupling strength Γ between the molecule and electrode. Baldea, 118,119 Frisbie, 22,45,49,120−123 and Yu et al 124,125 have proved that single-level model can fit well the experimental I−V characteristics. Meanwhile, ε fitting extracted from single-level model matches ε UPS measured using the UPS for oligophenylene thiol and alkanethiol systems, 45,120 confirming the effectiveness of the single-level model.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

Amine-Anchored Aromatic Self-Assembled Monolayer Junction: Structure and Electric Transport Properties

Tian

Martine

et al. 2021

Langmuir

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We studied the structure and transport properties of aromatic amine self-assembled monolayers (NH2-SAMs) on an Au surface. The oligophenylene and oligoacene amines with variable lengths can form a densely packed and uniform monolayer under proper assembly conditions. Molecular junctions incorporating an eutectic Ga–In (EGaIn) top electrode were used to characterize the charge transport properties of the amine monolayer. The current density J of the junction decreases exponentially with the molecular length (d), as J = J 0 exp(−βd), which is a sign of tunneling transport, with indistinguishable values of J 0 and β for NH2-SAMs of oligophenylene and oligoacene, indicating a similar molecule–electrode contact and tunneling barrier for two groups of molecules. Compared with the oligophenylene and oligoacene molecules with thiol (SH) as the anchor group, a similar β value (∼0.35 Å‑1) of the aromatic NH2-SAM suggests a similar tunneling barrier, while a lower (by 2 orders of magnitude) injection current J 0 is attributed to lower electronic coupling Γ of the amine group with the electrode. These observations are further supported by single-level tunneling model fitting. Our study here demonstrates the NH2-SAMs can work as an effective active layer for molecular junctions, and provide key physical parameters for the charge transport, paving the road for their applications in functional devices.

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A novel route to get functionality in nanoelectronics: Controlling the charge transport by the subtle impact of the coverage of self-assembled monolayers on the conformation of floppy molecules adsorbed on metallic electrodes

Bâldea

2019

Applied Surface Science

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Specific issues related to the law of corresponding states for the charge transport in molecular junctions based on graphene electrodes

Cited by 3 publications

References 53 publications

Quantifying Molecular Structure-Tunneling Conductance Relationships: Oligophenylene Dimethanethiol vs Oligophenylene Dithiol Molecular Junctions

Quantifying Molecular Structure-Tunneling Conductance Relationships: Oligophenylene Dimethanethiol vs Oligophenylene Dithiol Molecular Junctions

Amine-Anchored Aromatic Self-Assembled Monolayer Junction: Structure and Electric Transport Properties

A novel route to get functionality in nanoelectronics: Controlling the charge transport by the subtle impact of the coverage of self-assembled monolayers on the conformation of floppy molecules adsorbed on metallic electrodes

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