The effect of supporting electrolyte on the electron transfer at mixed self-assembled monolayers containing ferrocene moieties

Shiota, Koki; Osakai, Toshiyuki

doi:10.1016/j.jelechem.2015.07.004

Cited by 4 publications

(1 citation statement)

References 32 publications

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“…This observation indicates that the latter are more difficult to oxidize than the former, which is, as we have shown before, ,, associated with the packing energy of the SAMs. Densely packed monolayers are more difficult to oxidize because more energy is required to rearrange SAMs during the redox processes, which involves conformational changes and pairing of ClO 4 – with the Fc + . − From these observations, we conclude that the HS-C 1 -DPA-C 3 -Fc precursor yields SAMs that are better packed and have higher surface coverage values than those of SAMs derived from the HS-DPA-C 3 -Fc precursor and that SAMs formed from ethanol are more homogeneous than those SAMs formed from toluene (which could be related to intercalation of toluene via the hydrogen−π interactions between the DPA units and toluene molecules in the SAMs during the SAM formation process). , …”

Section: Resultsmentioning

confidence: 93%

Unraveling the Failure Modes of Molecular Diodes: The Importance of the Monolayer Formation Protocol and Anchoring Group to Minimize Leakage Currents

Wang

Jiang

et al. 2019

J. Phys. Chem. C

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The failure modes of molecular junctions have been only sporadically investigated, but they are important to understand so they can be prevented and molecular junctions can be optimized. Although it is commonly accepted that the performance and electrical characteristics of molecular tunneling junctions depend strongly on the supramolecular structure of the molecules inside the junctions, how sensitive molecular junctions are to small supramolecular changes and the factors that cause disorder are poorly understood for most types of molecular junctions. This paper shows that the performance of a large-area molecular diode depends on the choice of the anchoring group and solvent used for the formation of the self-assembled monolayer (SAM) in which both affect the surface coverage and the occurrence of disordered SAM domains. As a result, the rectification ratio was reduced by more than a factor of 10 across a series of molecular diodes, containing a diphenylacetylene backbone and a ferrocenyl terminus. The diodes failed because of leakage currents flowing across defective parts in the SAM lowering the rectification ratios, while the yield in working junctions or the electronic structure of the SAMs was remarkably insensitive to defects inside the SAMs. Thus, a judicious choice of anchoring group and solvent used in the SAM formation process can result in a 10-fold improvement in the performance of molecular diodes.

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