scholarly journals Electron and heat transport in porphyrin-based single-molecule transistors with electro-burnt graphene electrodes

2015 ◽  
Vol 6 ◽  
pp. 1413-1420 ◽  
Author(s):  
Hatef Sadeghi ◽  
Sara Sangtarash ◽  
Colin J Lambert
Keyword(s):  
Density Functional Theory ◽  
Single Molecule ◽  
Fermi Energy ◽  
Density Functional ◽  
Function Method ◽  
Voltage Characteristic ◽  
Frontier Orbitals ◽  
Current Voltage Characteristic ◽  
Functional Theory ◽  
Current Voltage

We have studied the charge and thermal transport properties of a porphyrin-based single-molecule transistor with electro-burnt graphene electrodes (EBG) using the nonequilibrium Green’s function method and density functional theory. The porphyrin-based molecule is bound to the EBG electrodes by planar aromatic anchor groups. Due to the efficient π–π overlap between the anchor groups and graphene and the location of frontier orbitals relative to the EBG Fermi energy, we predict HOMO-dominated transport. An on–off ratio as high as 150 is predicted for the device, which could be utilized with small gate voltages in the range of ±0.1 V. A positive thermopower of +280 μV/K is predicted for the device at the theoretical Fermi energy. The sign of the thermopower could be changed by tuning the Fermi energy. By gating the junction and changing the Fermi energy by +10 meV, this can be further enhanced to +475 μV/K. Although the electrodes and molecule are symmetric, the junction itself can be asymmetric due to different binding configurations at the electrodes. This can lead to rectification in the current–voltage characteristic of the junction.

scholarly journals Transport properties of the lateral multilayer/monolayer PtSe2 diode

2021 ◽  
Author(s):  
F. zandvakili ◽  
M. Berahman
Keyword(s):  
Density Functional Theory ◽  
Green Function ◽  
Density Functional ◽  
Reverse Bias ◽  
Forward Bias ◽  
Voltage Characteristic ◽  
Density Of State ◽  
Current Voltage Characteristic ◽  
Functional Theory ◽  
Current Voltage

Abstract A heterostructure of trilayer/monolayer platinum diselenide has been introduced and further studied. Applying the non-equilibrium green function tuned with density functional theory, it has been shown that such a junction forms a diode structure. The current voltage characteristic shows proper diode characteristics in nanoscale. Using the transmission spectrum and projected density of state, we have demonstrated that in forward bias, the conduction band and the valence band are aligned. Therefore, the possibility of tunneling enhances and this leads to the increase of current while in reverse bias such a possibility does not exist. We have also investigated the atoms of the junction and have identified the effective ones in the transmission.

Effects of different tailoring graphene electrodes on the rectification and negative differential resistance of molecular devices

2018 ◽  
Vol 32 (29) ◽  
pp. 1850323
Author(s):  
Ting Ting Zhang ◽  
Cai Juan Xia ◽  
Bo Qun Zhang ◽  
Xiao Feng Lu ◽  
Yang Liu ◽  
...  
Keyword(s):  
Electronic Transport ◽  
Negative Differential Resistance ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Differential Resistance ◽  
Voltage Characteristic ◽  
Molecular Devices ◽  
Current Voltage Characteristic ◽  
Functional Theory ◽  
Current Voltage

The electronic transport properties of oligo p-phenylenevinylene (OPV) molecule sandwiched with symmetrical or asymmetric tailoring graphene nanoribbons (GNRs) electrodes are investigated by nonequilibrium Green’s function in combination with density functional theory. The results show that different tailored GNRs electrodes can modulate the current–voltage characteristic of molecular devices. The rectifying behavior can be observed with respect to electrodes, and the maximum rectification ratio can reach to 14.2 in the asymmetric AC–ZZ GNRs and ZZ–AC–ZZ GNRs electrodes system. In addition, the obvious negative differential resistance can be observed in the symmetrical AC-ZZ GNRs system.

scholarly journals Giant magnetoresistance and spin Seebeck coefficient in zigzag α-graphyne nanoribbons

Nanoscale ◽  
2014 ◽  
Vol 6 (19) ◽  
pp. 11121-11129 ◽  
Author(s):  
Ming-Xing Zhai ◽  
Xue-Feng Wang ◽  
P. Vasilopoulos ◽  
Yu-Shen Liu ◽  
Yao-Jun Dong ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Green's Function ◽  
Density Functional ◽  
Function Method ◽  
Giant Magnetoresistance ◽  
Functional Theory ◽  
Non Equilibrium Green’S Function ◽  
Non Equilibrium

We investigate the spin-dependent electric and thermoelectric properties of ferromagnetic zigzag α-graphyne nanoribbons (ZαGNRs) using density-functional theory combined with non-equilibrium Green's function method.

Transition metal-containing molecular devices: controllable single-spin negative differential thermoelectric resistance effects under gate voltages

2019 ◽  
Vol 21 (9) ◽  
pp. 5243-5252 ◽  
Author(s):  
Xifeng Yang ◽  
Fangxin Tan ◽  
Yaojun Dong ◽  
Hailin Yu ◽  
Yushen Liu
Keyword(s):  
Density Functional Theory ◽  
Green Function ◽  
Transition Metal ◽  
Density Functional ◽  
Function Method ◽  
Graphene Nanoribbon ◽  
Molecular Devices ◽  
Functional Theory ◽  
Green Function Method ◽  
Single Spin

Based on the non-equilibrium Green function method combined with density functional theory, we investigate the spin-resolved transport through transition metal (TM) (= Cr, Mn, Fe and Ru)-containing molecular devices in the presence of zigzag graphene nanoribbon (ZGNR) electrodes.

The Local Structure and I-V Characteristics of Chromium Doped Semiconducting Boron Carbide

2011 ◽  
Vol 1307 ◽  
Author(s):  
Jing Liu ◽  
P. A. Dowben ◽  
Guangfu Luo ◽  
Wai-Ning Mei ◽  
Anil Kumar Rajapitamahuni ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Boron Carbide ◽  
Local Structure ◽  
Density Functional ◽  
Room Temperature ◽  
Magnetic Ordering ◽  
Computational Results ◽  
Functional Theory ◽  
Spin Configuration ◽  
Current Voltage

ABSTRACTThe local spin configuration and band structure of chromium doped boron carbide calculated by density functional theory suggests local magnetic ordering. While the long range dopant position appears random in the boron carbide semiconductor, the local position and initial empirical/computational results suggest the promise of large magneto-resistive effects. The chromium doped boron carbide thin films, fabricated by boron carbide-chromium co-deposition, were studied by current-voltage (I-V) characteristics measurements. The results provide some reason to believe that magneto-resistive effects are indeed present at room temperature.

Density Functional Theory Calculations of Arsenic(III) Structures on Perfect TiO2 Anatase (1 0 1) Surface

2011 ◽  
Vol 233-235 ◽  
pp. 491-494 ◽  
Author(s):  
Lin Yu ◽  
Yue Liu ◽  
Zhi Gang Wei ◽  
Gui Qiang Diao ◽  
Ming Sun ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Adsorption Energy ◽  
Density Functional ◽  
Function Method ◽  
Photocatalytic Oxidation ◽  
Density Functional Theory Calculations ◽  
Functional Theory ◽  
Low Concentrations ◽  
The Density Functional Theory ◽  
The World

There are many areas in the world where the ground water has been contaminated by arsenic. One process to purify the water is to use TiO2 to adsorb the arsenic. As the TiO2 surface can be cleaned and reused, it has a promising potential as a water purifier. In this paper, the plane-wave function method, based on the density functional theory, has been used to calculate the structures of arsenic(III) on a perfect TiO2 anatase (1 0 1) surface. All the arsenic(III) solution species such as H3AsO3, H2AsO3-1, HAsO3-2 and AsO3-3 are put onto the surface with many different possible structures to obtain the adsorption energy. Based on the adsorption energy, the bidentate binuclear (BB) adsorption configurations of arsenic(III) on the surface are more favorable at low concentrations, whereas BB form and monodentate mononuclear (MM) form may coexist at higher concentrations. The models and results fit well with published experimental results. The results and conclusions will be of benefit to further research on arsenite adsorption and its photocatalytic oxidation on a TiO2 surface.

A density functional theory approach to the magnetic properties of a coupled single-molecule magnet (Mn7)2 complex — An entangled qubit pair candidate

2013 ◽  
Vol 91 (9) ◽  
pp. 866-871 ◽  
Author(s):  
Silvia Gómez-Coca ◽  
Eliseo Ruiz
Keyword(s):  
Density Functional Theory ◽  
Single Molecule ◽  
Exchange Coupling ◽  
Density Functional ◽  
Relative Strength ◽  
Coupling Constants ◽  
Basis Set ◽  
Theory Approach ◽  
Functional Theory ◽  
Spin Configuration

The exchange coupling constants of a Mn14 complex constituted by two weakly coupled Mn7 moieties were calculated using two different density functional theory (DFT) approaches: the Perdew–Burke–Ernzerhof (PBE) functional with a numerical basis set and the hybrid Becke, three-parameter Lee–Yang–Parr (B3LYP) functional employed with a Gaussian basis set. The sign and relative strength of the exchange coupling constants calculated with both methods were consistent; as expected, the values calculated with the PBE functional were slightly overestimated, as corroborated by comparison with the experimental magnetic susceptibility curve. Both methods gave a ground spin configuration of S = 3/2 for the Mn7 moiety, which was weakly antiferromagnetically coupled with the other Mn7 fragment, leading to an S = 0 ground spin configuration for the entire Mn14 complex.

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