What is it about?

Electronic transport through a molecular tunnel junction composed of two polyyne-type carbynes separated by distance (4 Å ≥ dn ≥ 2.1 Å) based on Density Functional Theory/Non-Equilibrium Green’s Function (DFT/NEGF). The frontier molecular orbitals and bond lengths of the polyyne (dC–C ≈ 1.36 Å, dC≡C ≈ 1.26 Å) at 0.0 V become equal to those in cumulene-type carbynes (dC=C ≈ 1.28 Å) at 0.9 V occurring a semiconductor–metal transition for dn < 4 Å. I–V (dI/dV–V) curve presents switching behaviour up to 0.6 V and after a diode behaviour favoured as dn decreases, that is, to 4.0 Å is 3.3 nA (5 nS) while for 2.1 Å is 3750 nA (1500 nS) showing metallic nature. The log(I)–V [log(dI/dV)–V] curve exhibits the behaviour for low bias voltage while the I–dn curve is exhibited for high bias voltage.

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Why is it important?

Carbynes have gained highlight due to their unique properties and applications in molecular electronics exhibiting resonant tunnel effect. So, we investigated tunneling at molecular junctions plays a role in the electronic transport of 1-D systems.


The exponential expression for G(d) fits perfectly with the Gmax result obtained with DFT/NEGF calculations. Transition Voltage Spectroscopy (TVS) confirms rectangular barrier and direct tunneling for Vd–s < ϕB/e playing a tunneling rule for electronic transport of these 1-D systems. So, investigate the electronic transport via tunneling in other 1D molecuar systems becomes trivial.

Prof. Dr. Carlos Alberto Brito da Silva Jr.
Universidade Federal do Para

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This page is a summary of: Tunneling rules for electronic transport in 1-D systems, Molecular Physics, September 2021, Taylor & Francis, DOI: 10.1080/00268976.2021.1976427.
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