PD Dr. habil. Artur Erbe, Division Head “Scaling Phenomena” and Group Leader “Transport Phenomena in Nanostructures”, Institute for Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden–Rossendorf, Germany

Switching and Doping in Single Molecule Electronics

In order to design electrical circuits which are based on the properties of single molecules, reliable contacts to single organic molecules have to be built. The properties of those junctions need to be characterized. We have demonstrated that the mechanically controllable break junction (MCBJ) technique can be successfully used to determine the properties of electronic transport through single organic molecules and that the participating molecular energy levels and the metal-molecule coupling can be characterized using this technique¹. Further developments are based on the use of more complex molecules, which can, for example, be used as single molecule switches^2,3.

We present the first demonstration of a single molecule junction, in which the molecule is switched in situ from the non-conducting “off”-state to the conducting “on”-state. The conductance of the on-state can be tuned by varying the molecular structure showing that we can fabricate and characterize a well-controlled single-molecule switch. Further development towards realistic electronic circuits based on single molecule devices requires a broad range tuning of the conductance values, especially towards high conductance values. We show that the incorporation of metal ions into a single molecule can increase the conductance of the molecular junctions by orders of magnitude. This method resembles doping of semiconducting materials as it is used in electronic circuits.

In combination, our developments show that current on the single molecule level can be precisely controlled. Therefore, the structures presented here can be regarded as steps towards applications using single molecule electronics.

References

1. Zotti, L. A. et al. Revealing the Role of Anchoring Groups in the Electrical Conduction Through Single-Molecule Junctions. Small 6, 1529 (2010).
2. Sendler, T., et al. Light-Induced Switching of Tunable Single-Molecule Junctions. Advanced Science 2015, 1500017.
3. Kim, Y. et al. Charge Transport Characteristics of Diarylethene Photoswitching Single-Molecule Junctions. Nano Lett 12, 3736 (2012).

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