Study On Electrical Transport Of Several Types Of Aromatic Single-molecule Structures

With the development of society,the requirements for devices are getting higher and higher,and traditional semiconductor devices can no longer meet the needs of the development.With the continuous improvement of integration,the miniaturization of devices is necessary.At the same time,more and more nano materials and nano structures are emerging.Based on this,we use density functional theory combined with non-equilibrium Green's function to study the electron transport properties of several typical aromatic molecular nanostructures after coupling with metal electrodes,i.e.,iron-based hybrid aromatic single molecules,ruthenium-doped organic molecule,and molecular cage structure composed of anti-aromatic small molecules.The electronic structure and transport phenomena presented by the systems are analyzed,and the internal physical mechanism is explored.First,we studied the electronic properties of iron-doped aromatic single-molecule structures,and systematically analyzed the effects of molecular length and iron atom chain length on the transport properties,and discovered the phenomenon of spin polarization,showing good robustness.By applying a gate voltage,the spin polarization ratio can be modulatd progressively from 100% to-100%.Secondly,we investigated polyacetylene chain-like molecules doped with an organometallic ruthenium atom.The changes in the chain length of the carbon atoms on both sides of the structure,and the corresponding influence on electron transport,are studied.It is found that no matter how the numbers of carbon atoms at both ends change,there is negative differential resistance feature in the structure,showing good robustness.Finally,we studied the self-assembled anti-aromatic molecular cage structure,and contact sites are selected to couple with gold electrodes.One finds that it is spin-up polarized at the Fermi level in the transmission spectra,which can be used as a spin-up filter.Moreover,there are also fully polarized transmission peaks with opposite spins near the Fermi level.Thus,electrically-controlled dual spin filter are expected to be realized based on such a system,through applying a gate voltage.