Ballistic phonon thermal conductance in graphene nanoribbons

2013 ◽  
Vol 31 (4) ◽  
pp. 04D104 ◽  
Author(s):  
Hiroki Tomita ◽  
Jun Nakamura
Keyword(s):  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Phonon Thermal Conductance

Strained effects on the thermal conductance of flexural and in-plane modes in graphene nanoribbons

2019 ◽  
Vol 33 (31) ◽  
pp. 1950383
Author(s):  
Bengang Bao ◽  
Gao-Hua Liao ◽  
Jun He ◽  
Chang-Ning Pan
Keyword(s):  
Transport Properties ◽  
Phonon Mode ◽  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Low Frequency ◽  
Phonon Transport ◽  
Frequency Region ◽  
Function Approach ◽  
Non Equilibrium Green’S Function ◽  
Plane Mode

Ballistic thermal transport properties in graphene nanoribbon modulated with strain are investigated by non-equilibrium Green’s function approach. The results show that the strain can suppress the phonon transport of flexural phonon mode (FPM) and enhance the phonon transport of in-plane mode (IPM) in low-frequency region, leading to the reduction in the thermal conductance of FPM and the enhancement in the thermal conductance of IPM. The total thermal conductance is decreased by strain as the reduction in the thermal conductance of FPM overcomes the enhancement in the thermal conductance of IPM.

The influence of flaws on phonon thermal conductance in a dielectric quantum wire

2007 ◽  
Vol 40 (22) ◽  
pp. 7159-7165 ◽  
Author(s):  
Yan Wang ◽  
Ling-Ling Wang ◽  
Li-Ming Tang ◽  
BS Zou ◽  
Li-Hua Zhao
Keyword(s):  
Quantum Wire ◽  
Thermal Conductance ◽  
Phonon Thermal Conductance

scholarly journals Impurity Substitution Enhances Thermoelectric Figure of Merit in Zigzag Graphene Nanoribbons

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Saeideh Ramezani Akbarabadi ◽  
Mojtaba Madadi Asl
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Electrical Conductance ◽  
Thermal Conductance ◽  
Simultaneous Increase ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Zigzag Graphene Nanoribbons

The thermoelectric properties of zigzag graphene nanoribbons (ZGNRs) are sensitive to chemical modification. In this study, we employed density functional theory (DFT) combined with the nonequilibrium green’s function (NEGF) formalism to investigate the thermoelectric properties of a ZGNR system by impurity substitution of single and double nitrogen (N) atoms into the edge of the nanoribbon. N-doping changes the electronic transmission probability near the Fermi energy and suppresses the phononic transmission. This results in a modified electrical conductance, thermal conductance, and thermopower. Ultimately, simultaneous increase of the thermopower and suppression of the electron and phonon contributions to the thermal conductance leads to the significant enhancement of the figure of merit in the perturbed (i.e., doped) system compared to the unperturbed (i.e., nondoped) system. Increasing the number of dopants not only changes the nature of transport and the sign of thermopower but also further suppresses the electron and phonon contributions to the thermal conductance, resulting in an enhanced thermoelectric figure of merit. Our results may be relevant for the development of ZGNR devices with enhanced thermoelectric efficiency.

Significantly enhanced thermoelectric performance of molecular junctions by the twist angle dependent phonon interference effect

2020 ◽  
Vol 8 (23) ◽  
pp. 11884-11891 ◽  
Author(s):  
Yu-Jia Zeng ◽  
Dan Wu ◽  
Xuan-Hao Cao ◽  
Ye-Xin Feng ◽  
Li-Ming Tang ◽  
...  
Keyword(s):  
Interference Effect ◽  
Twist Angle ◽  
Thermal Conductance ◽  
Molecular Junctions ◽  
Thermoelectric Performance ◽  
Phonon Thermal Conductance

The twist angle can induce phonon interference effect in the intermediately coupled molecular junctions and significantly suppress phonon thermal conductance.

Enhanced thermoelectric properties in nanowires of InAs modulated with multiple-stub structures

2019 ◽  
Vol 9 (5) ◽  
pp. 498-502
Author(s):  
Changning Pan ◽  
Jun He ◽  
Zhiming Liu ◽  
Kaixing Shi
Keyword(s):  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Thermal Conductance ◽  
Volume Ratio ◽  
Electronic Density ◽  
Energy Filtering ◽  
Carrier Energy ◽  
Inas Nanowires ◽  
Scattering Matrix Method ◽  
Phonon Thermal Conductance

The thermoelectric properties of InAs nanowires modulated with the multiple-stub structures are studied using the scattering-matrix method. Owing to the very large surface-to-volume ratio, both the phonon and electron transport sensitively depend on the geometric structure. Carrier energy filtering which locally distorts electronic density of states strongly enhances the thermopower. Thus optimized thermopower, together with the significant reduction of the phonon thermal conductance, yields the high thermoelectric figure of merit ZT to 0.3∼1.9.

Topological symmetry-induced width dependence of thermal conductance of edge-reconstructed graphene nanoribbons

2014 ◽  
Vol 47 (26) ◽  
pp. 265303 ◽  
Author(s):  
Jinghua Lan ◽  
Yongqing Cai ◽  
Gang Zhang ◽  
Jian-Sheng Wang ◽  
Yong-Wei Zhang
Keyword(s):  
Graphene Nanoribbons ◽  
Thermal Conductance

Thermal conductance attributed to phonon and electron in graphene nanoribbon

2014 ◽  
Vol 28 (18) ◽  
pp. 1450116 ◽  
Author(s):  
En-Jia Ye ◽  
Yi-Jian Shi ◽  
Lihong Shi ◽  
Xuean Zhao
Keyword(s):  
Low Temperature ◽  
Heat Transport ◽  
Energy Band ◽  
Function Method ◽  
Energy Transport ◽  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Square Lattice ◽  
Heat Current ◽  
Electron Contribution

In this work, the energy transport of phonon and electron in graphene nanoribbons (GNRs) are investigated by the nonequilibrium Green's function method without considering the interaction of phonon and electron. The heat current of phonon contribution comes from the gradient of temperature. While for the electron contribution, it stems from the gradient of both temperature and electrochemical potential. The corresponding intermediate functions satisfy the Onsager relationship. Thermal conductances are calculated in GNR and compared to those in square lattice ribbon model respectively. It is found that both the phonon and electron thermal conductances in square lattice ribbon are smaller than those in GNRs at low temperature and surpass those in armchair and zigzag GNRs respectively, as the temperature increases. Meanwhile, the heat transport is related to the edges of GNRs. These phenomena depend on their dispersion relations and energy band structures.

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