Molecular Diodes with Rectification Ratios of Nearly Six Orders of Magnitude
Christian A. Nijhuis, Department of Chemistry, National University of Singapore
One of the major goals of molecular electronics is to relate the performance and electronic function of molecular devices to the chemical structure and intermolecular interactions of the organic molecules inside them. Molecular electronic devices are complex physical-organic systems that consist of at least two electrodes, the organic component, and two (different) organic/inorganic interfaces. Singling out the contribution of each of these components to the device performance is not straightforward. Besides, fabrication of molecular junctions is still challenging and defects have to be minimized.
During the talk, I will discuss our recent progress of molecular diodes based on self-assembled monolayers (SAMs) of ferrocene-alkanethiolates of the form H(CH2)nFc (Fc = ferrocene) sandwiched between two electrodes. I will discuss in detail how we fabricate the junctions (using the well-characterized “EGaIn”-technique) and characterize our junctions and SAMs. We have investigated the various sources of defects in the junctions caused by the impurities in the SAM precursors, defects in the electrode material, or subtle changes to the electronic and supramolecular structure of the junctions. We used this accumulated knowledge to develop a well-performing diode that blocks the current in one direction of bias, but allows it to pass through in the other, with a difference of a factor of 6.3 x 105.[5,6]
We hope that our findings will help to guide future experiments and to explain why some on paper promising diodes had disappointing performances.
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2) Yuan, L.; jiang, L.; Thompson, D.; Nijhuis, C. A. J. Am. Chem. Soc. 2014, 136, 6554.
3) Yuan, L.; Nerngchamnong, N.; Cao, L.; Hamoudi, H.; Del Barco, E.; Roemer, M.; Sriramula, R.; Thompson, D.; Nijhuis, C. A. Nat. Commun. 2015, 6.
4) Nerngchanmnong, N.; Yuan, L.; Qi, D. C.; Jiang, L.; Thompson, D.; Nijhuis, C. A. Nat. Nanotechnol. 2013, 8, 113.
5) Yuan, L.; Breuer, R.; Jiang, L.; Schmittel, M.; Nijhuis, C. A. Nano Lett. 2015, 15, 5506.
6) Chen, X.; Roemer, M.; Yuan, L.; Wei, D.; Del Barco, E.; Thompson, D.; Nijhuis, C.A. submitted
7) Thompson, D.; Nijhuis, C. A. Acc. Chem. Res. 2016, 49, 2061