Thermoelectric transport properties in graphene connected molecular junctions

Abstract

We study the electronic contribution to the main thermoelectric properties of a molecular junction consisting of a single quantum dot coupled to graphene external leads. The system electrical conductivity (G), Seebeck coefficient ($S$), and the thermal conductivity ($\kappa$), are numerically calculated based on a Green's function formalism that includes contributions up to the Hartree-Fock level. We consider the system leads to be made either of pure or gapped-graphene. To describe the free electrons in the gapped-graphene electrodes we used two possible scenarios, the massive gap scenario, and the massless gap scenario, respectively. In all cases, the Fano effect is responsible for a strong violation of the Wiedemann-Franz law and we found a substantial increase of the system figure of merit $ZT$ due to a drastic reduction of the system thermal coefficient. In the case of gapped-graphene electrodes, the system figure of merit presents a maximum at an optimal value of the energy gap of the order of $\Delta /D\sim$ 0.002 (massive gap scenario) and $\Delta /D\sim$ 0.0026 (massless gap scenario). Additionally, for all cases, the system figure of merit is temperature dependent.

arXiv comment7 pages, 6 figures

References in corpus (22)

• The electronic properties of graphene
• Thermal Properties of Graphene, Carbon Nanotubes and Nanostructured Carbon Materials
• Energy Band Gap Engineering of Graphene Nanoribbons
• Electronic transport in two dimensional graphene
• Substrate-induced band gap opening in epitaxial graphene
• Graphene Nano-Ribbon Electronics
• Electronic States of Graphene Nanoribbons
• Spin qubits in graphene quantum dots
• Quantum thermal transport in nanostructures
• Strain-induced enhancement of thermoelectric performance in a ZrS2 monolayer
• Anomalous orbital magnetism in Dirac-electron systems: Role of pseudo-spin paramagnetism
• Large enhancement of thermoelectric effects in a double quantum dot system due to interference and Coulomb correlation phenomena
• Symmetry Breaking in Few Layer Graphene Films
• High Thermoelectric Power Factor in Graphene/hBN Devices
• Origin of the energy bandgap in epitaxial graphene
• Thermopower of Aharonov-Bohm Interferometer with a Quantum Dot
• Single or multi-flavor Kondo effect in graphene
• Spectroscopic Signatures of Massless Gap Opening in Graphene
• Thermoelectric transport properties of a T-shaped double quantum dot system in the Coulomb blockade regime
• Spectral scaling and quantum critical behaviour in the pseudogap Anderson model
• Density Functional Theory of the Seebeck coefficient in the Coulomb blockade regime
• Electronic Green's functions in a T-shaped multi-quantum dot system

Cited by in corpus (1)

• Nonequilibrium Kondo effect in a graphene-coupled quantum dot in the presence of a magnetic field