Topology effects of interface and gate voltage on electrical transport through the CNT/C60/CNT junction using the Green’s function method

Dong

Phys. Chem. Chem. Phys.

et al. 2016

This study is built on density functional calculations in combination with the non-equilibrium Green's function, and we probe the thermoelectric transport mechanisms through C molecules anchored to Al nano-electrodes in three different ways, such as, the planar, pyramidal, and asymmetric surfaces. When the electrode is switched from the planar and pyramidal surfaces, the electrical conductance (σ) and electron's thermal conductance (κ) decrease almost two orders of magnitude due to the reduction of the molecule-electrode contact coupling, whereas the Seebeck coefficients (S) are reduced by ∼55%. Furthermore, the maximum electron's thermoelectric figure of merit (ZT = SσT/κ, assuming a vanishing phonon's thermal conductance) is about 0.12 in the asymmetric junction. In particular, all σ, S, κ, and ZT increase along with the average temperature (T) in all C-junctions, although their growth is really quite negligible in the pyramidal junction because the Fermi level is far away from the frontier orbitals. In addition, when the strain increases from the compressive (-1.0 Å) to tensile (1.0 Å) strain, the Seebeck coefficient in the planar junction increases drastically, while the Seebeck coefficients in the asymmetric and pyramidal junctions reach their maximum values at 0.2 Å tensile and -0.4 Å compressive strains, respectively. This is because the Seebeck coefficient is inversely proportional to the magnitudes and proportional to the slopes of the transmission spectrum around the Fermi level. Finally, it is found that the shift of the Fermi level is an effective scheme to obtain the maximum ZT of any molecular junction, including fullerene-based junctions.

Section: Effect Of Fermi Level Shiftmentioning

confidence: 99%

Thermoelectric properties of fullerene-based junctions: a first-principles study

Dong

Phys. Chem. Chem. Phys.

et al. 2016

“…They found that the I-V characteristics could be changed from metallic behavior to semiconducting by a gate potential, thereby forming a field-effect molecular current switch. Saffarzaden 21 and Shokri et al 22 respectively investigated electron transport across a carbon molecular junction consisting of a C 60 molecule attached to two one-dimensional electrodes and semi-infinite metallic open-end CNT leads. They found that a gate voltage could shift the molecular levels, where the electron conduction could be controlled by adjusting the related parameters.…”

Section: Introductionmentioning

confidence: 99%

Rectifying behaviors of an Au/(C20)2/Au molecular device induced by the different positions of gate voltage

Cui

et al. 2012

RSC Adv.

The electronic transport properties of a gated Au/(C 20 ) 2 /Au molecular device are studied using nonequilibrium Green's function in combination with density functional theory. The results show that different applied positions of the external transverse gate voltage can effectively tune the currentvoltage (I-V) characteristic of molecular devices. Rectifying behaviors of the device can be realized when the gate voltage is applied asymmetrically on the left C 20 molecule, and the rectification directions can also be modulated by the positive or negative value of the gate voltage. These results provide an important theoretical support to experiments and the design of a molecular rectifier.

Journal of Applied Physics

“…3 Particularly, several authors have studied the molecular junctions of the C 60 fullerene under different types of connections, such as a substrate and a STM tip, 4,5 one-dimensional leads, 6 carbon nanotubes (CNTs), 7 gold clusters, 8 or break junctions. 9 Furthermore, the stability and strong hybridization of C 60 with metallic surfaces make it also a feasible anchoring group with high conductance.…”

Section: Introductionmentioning

confidence: 99%

Quantum transport through single and multilayer icosahedral fullerenes

Lovey

Romero

2013

We use a tight-binding Hamiltonian and Green functions methods to calculate the quantum transmission through single-wall fullerenes and bilayered and trilayered onions of icosahedral symmetry attached to metallic leads. The electronic structure of the onion-like fullerenes takes into account the curvature and finite size of the fullerenes layers as well as the strength of the intershell interactions depending on to the number of interacting atom pairs belonging to adjacent shells. Misalignment of the symmetry axes of the concentric iscosahedral shells produces breaking of the level degeneracies of the individual shells, giving rise some narrow quasi-continuum bands instead of the localized discrete peaks of the individual fullerenes. As a result, the transmission function for non symmetrical onions is rapidly varying functions of the Fermi energy. Furthermore, we found that most of the features of the transmission through the onions are due to the electronic structure of the outer shell with additional Fano-like antiresonances arising from coupling with or between the inner shells. V C 2013 AIP Publishing LLC. [http://dx