Impurity Substitution Enhances Thermoelectric Figure of Merit in 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.

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Enhanced thermoelectric figure of merit in edge-disordered zigzag graphene nanoribbons

Physical Review B ◽

10.1103/physrevb.81.113401 ◽

2010 ◽

Vol 81 (11) ◽

Cited By ~ 212

Author(s):

H. Sevinçli ◽

G. Cuniberti

Keyword(s):

Figure Of Merit ◽

Graphene Nanoribbons ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Zigzag Graphene Nanoribbons

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Enhancing the thermoelectric figure of merit in engineered graphene nanoribbons

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.6.119 ◽

2015 ◽

Vol 6 ◽

pp. 1176-1182 ◽

Cited By ~ 43

Author(s):

Hatef Sadeghi ◽

Sara Sangtarash ◽

Colin J Lambert

Keyword(s):

Thermoelectric Properties ◽

Fermi Energy ◽

Figure Of Merit ◽

Graphene Nanoribbons ◽

The Other ◽

Monolayer Graphene ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Inner Surface ◽

Current Flows

We demonstrate that thermoelectric properties of graphene nanoribbons can be dramatically improved by introducing nanopores. In monolayer graphene, this increases the electronic thermoelectric figure of merit ZT e from 0.01 to 0.5. The largest values of ZT e are found when a nanopore is introduced into bilayer graphene, such that the current flows from one layer to the other via the inner surface of the pore, for which values as high as ZT e = 2.45 are obtained. All thermoelectric properties can be further enhanced by tuning the Fermi energy of the leads.

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Enhancement of thermoelectric figure of merit in zigzag graphene nanoribbons with periodic edge vacancies

International Journal of Modern Physics B ◽

10.1142/s0217979217501247 ◽

2017 ◽

Vol 31 (15) ◽

pp. 1750124 ◽

Cited By ~ 3

Author(s):

D. V. Kolesnikov ◽

O. G. Sadykova ◽

V. A. Osipov

Keyword(s):

Seebeck Coefficient ◽

Figure Of Merit ◽

Nearest Neighbor ◽

Graphene Nanoribbons ◽

Tight Binding ◽

Dynamical Matrix ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Tight Binding Approximation ◽

Zigzag Graphene Nanoribbons

The influence of periodic edge vacancies and antidot arrays on the thermoelectric properties of zigzag graphene nanoribbons (ZGNRs) are investigated. Using Green’s function method, the tight-binding approximation for the electron Hamiltonian and the 4th nearest neighbor approximation for the phonon dynamical matrix, we calculate the Seebeck coefficient and the thermoelectric figure of merit. It is found that, at a certain periodic arrangement of vacancies on both edges of zigzag nanoribbon, a finite band gap opens and almost twofold degenerate energy levels appear. As a result, a marked increase in the Seebeck coefficient takes place. It is shown that an additional enhancement of the thermoelectric figure of merit can be achieved by a combination of periodic edge defects with an antidot array.

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Spin thermoelectric effects of new-style one-dimensional carbon-based nanomaterials

Characterization and Application of Nanomaterials ◽

10.24294/can.v4i1.1323 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Yushen Liu ◽

Jinfu Feng ◽

Xuefeng Wang

Keyword(s):

Figure Of Merit ◽

Graphene Nanoribbons ◽

Thermal Conductance ◽

Transmission Function ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Effects ◽

Thermoelectric Figure ◽

One Dimensional ◽

Carbon Chains ◽

Carbon Based Nanomaterials

Based on first-principles methods, the authors of this paper investigate spin thermoelectric effects of one-dimensional spin-based devices consisting of zigzag-edged graphene nanoribbons (ZGNRs), carbon chains and graphene nanoflake. It is found that the spin-down transmission function is suppressed to zero, while the spin-up transmission function is about 0.25. Therefore, an ideal half-metallic property is achieved. In addition, the phonon thermal conductance is obviously smaller than the electronic thermal conductance. Meantime, the spin Seebeck effects are obviously enhanced at the low-temperature regime (about 80K), resulting in the fact that spin thermoelectric figure of merit can reach about 40. Moreover, the spin thermoelectric figure of merit is always larger than the corresponding charge thermoelectric figure of merit. Therefore, the study shows that they can be used to prepare the ideal thermospin devices.

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Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

Modern Physics Letters B ◽

10.1142/s0217984920500190 ◽

2019 ◽

Vol 34 (02) ◽

pp. 2050019 ◽

Cited By ~ 2

Author(s):

Y. Zhang ◽

M. M. Fan ◽

C. C. Ruan ◽

Y. W. Zhang ◽

X.-J. Li ◽

...

Keyword(s):

Thermal Conductivity ◽

Thermoelectric Properties ◽

Figure Of Merit ◽

Phonon Scattering ◽

Sintered Sample ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

The Third ◽

Ceramic Samples ◽

Optimum Formula

[Formula: see text] ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit [Formula: see text] of [Formula: see text]. The optimum [Formula: see text] value of 0.26 is achieved at 923 K by the third sintered sample.

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Effects of Ce filling fraction and Fe content on the thermoelectric properties of Co-rich CeyFexCo4−xSb12

Journal of Materials Research ◽

10.1557/jmr.2001.0109 ◽

2001 ◽

Vol 16 (3) ◽

pp. 837-843 ◽

Cited By ~ 66

Author(s):

Xinfeng Tang ◽

Lidong Chen ◽

Takashi Goto ◽

Toshio Hirai

Keyword(s):

Thermal Conductivity ◽

Thermoelectric Properties ◽

Figure Of Merit ◽

Single Phase ◽

Lattice Thermal Conductivity ◽

Hole Concentration ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Filling Fraction ◽

Fe Content

Single-phase filled skutterudite compounds, CeyFexCo4−xSb12 (x = 0 to 3.0, y = 0 to 0.74), were synthesized by a melting method. The effects of Fe content and Ce filling fraction on the thermoelectric properties of CeyFexCo4−xSb12 were investigated. The lattice thermal conductivity of Ce-saturated CeyFexCo4−xSb12, y being at the maximum corresponding to x, decreased with increasing Fe content (x) and reached its minimum at about x = 1.5. When x was 1.5, lattice thermal conductivity decreased with increasing Ce filling fraction till y = 0.3 and then began to increase after reaching the minimum at y = 0.3. Hole concentration and electrical conductivity of Cey Fe1.5Co2.5Sb12 decreased with increasing Ce filling fraction. The Seebeck coefficient increased with increasing Ce filling fraction. The greatest dimensionless thermoelectric figure of merit T value of 1.1 was obtained at 750 K for the composition of Ce0.28Fe1.52Co2.48Sb12.

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Thermoelectric Properties of CoSb3-based Skutterudite Compounds

MRS Proceedings ◽

10.1557/proc-1267-dd03-02 ◽

2010 ◽

Vol 1267 ◽

Author(s):

Adul Harnwunggmoung ◽

Ken Kurosaki ◽

Hiroaki Muta ◽

Shinsuke Yamanaka

Keyword(s):

Thermal Conductivity ◽

Thermoelectric Properties ◽

Figure Of Merit ◽

Room Temperature ◽

Lattice Thermal Conductivity ◽

Filling Ratio ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Alloy Scattering ◽

Skutterudite Compound

AbstractCoSb3 is known as a skutterudite compound that could exhibit high thermoelectric figure of merit. However, the thermal conductivity of CoSb3 is relatively high. In order to enhance the thermoelectric performance of this compound, we tried to reduce the thermal conductivity of CoSb3 by substitution of Rh for Co and by Tl-filling into the voids. The polycrystalline samples of (Co,Rh)Sb3 and Tl-filled CoSb3 were prepared and the thermoelectric properties such as the Seebeck coefficient, electrical resistivity, and thermal conductivity were measured in the temperature range from room temperature to 750 K. The Rh substitution for Co reduced the lattice thermal conductivity, due to the alloy scattering effect. The minimum value of the lattice thermal conductivity was 4 Wm-1K-1 at 750 K obtained for (Co0.7Rh0.3)Sb3. Also the lattice thermal conductivity rapidly decreased with increasing the Tl-filling ratio. T10.25Co4Sb12 exhibited the best ZT values; the maximum ZT was 0.9 obtained at 600 K.

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Enhancement of thermoelectric figure of merit by incorporation of large single crystals in Ca3Co4O9 bulk materials

Journal of Materials Research ◽

10.1557/jmr.2003.0226 ◽

2003 ◽

Vol 18 (7) ◽

pp. 1646-1651 ◽

Cited By ~ 31

Author(s):

Ryoji Funahashi ◽

Saori Urata ◽

Toyohide Sano ◽

Masaaki Kitawaki

Keyword(s):

Electrical Conductivity ◽

Composite Material ◽

Single Crystals ◽

Thermoelectric Properties ◽

Figure Of Merit ◽

Thermoelectric Figure Of Merit ◽

Bulk Materials ◽

Flux Method ◽

Thermoelectric Figure ◽

Grain Alignment

Having recently succeeded in synthesizing large single crystals of (Ca2CoO3)CoO2 (Co-349) with superior thermoelectric properties using a modified flux method, we have prepared a composite material of Co-349 powder and single crystals and examined its thermoelectric properties. The electrical conductivity σ of this composite, which contained 20 wt.% single crystals, was higher than that of a sample without the single crystals. While the achievable effect has yet to be fully realized, improved grain alignment and the effect of current bypassing grain boundaries through the large single crystals in the composite are thought to cause the increasing σ, which consequently results in an enhanced thermoelectric figure of merit of about 0.56 at 973 K in air.

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Thermoelectric Properties of a Wide–Gap Chalcopyrite Compound AgInSe2

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.519.188 ◽

2012 ◽

Vol 519 ◽

pp. 188-192 ◽

Cited By ~ 11

Author(s):

P.Z. Ying ◽

H. Zhou ◽

Y.L. Gao ◽

Y.Y. Li ◽

Y.P. Li ◽

...

Keyword(s):

Thermal Conductivity ◽

Electrical Conductivity ◽

Thermoelectric Properties ◽

Figure Of Merit ◽

Chemical Compositions ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Remarkable Improvement ◽

Wide Gap ◽

Chalcopyrite Compound

Here we report the thermoelectric properties of a wide–gap chalcopyrite compound AgInSe2, and observed the remarkable improvement in electrical conductivity σ, due to the bandgap (Eg = 1.12 eV) reduction compared to In2Se3. The improvement in σ is directly responsible for the enhancement of thermoelectric figure of merit ZT, though the thermal conductivity is much higher at 500 ~ 724 K. The maximum ZT value is 0.34 at 724 K, increasing by a factor of 4, indicating that this chalcopyrite compound is of a potential thermoelectric candidate if further optimizations of chemical compositions and structure are made.

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