Enhancing the Thermoelectric Figure of Merit by Low-Dimensional Electrical Transport in Phonon-Glass Crystals

Mi, Xue-Ya; Yu, Xiaoxiang; Kai-Lun, Yao; Huang, Xiaoming; Yang, Nuo; Lü, Jing-Tao

doi:10.1021/acs.nanolett.5b01491

Cited by 67 publications

(41 citation statements)

References 59 publications

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“…The calculated optimal ZT of pentacene and rubrene are 1.8 and 0.6 at room temperature, respectively [60]. Herringbone stacked BDT is predicted to have peculiar 1D band structure and an optimal ZT of 1.48 at room temperature [27]. Before closing, we combine PCN, g-CN1, g-CN2 and A-A stacked graphite, to search for the possible lattice structure that materials can have to obtain high crossplane ZT.…”

Section: Resultsmentioning

confidence: 99%

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Unexpectedly high cross-plane thermoelectric performance of layered carbon nitrides

Ding

et al. 2019

J. Mater. Chem. A

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Organic thermoelectric (TE) materials create a brand new perspective to search for high-efficiency TE materials, due to their small thermal conductivity. The overlap of pz orbitals, commonly existing in organic π-stacking semiconductors, can potentially result in high electronic mobility comparable to inorganic electronics. Here we propose a strategy to utilize the overlap of pz orbitals to increase the TE efficiency of layered polymeric carbon nitride (PCN). Through first-principles calculations and classical molecular dynamics simulations, we find that A-A stacked PCN has unexpectedly high cross-plane ZT up to 0.52 at 300 K, which can contribute to n-type TE groups. The high ZT originates from its one-dimensional charge transport and small thermal conductivity. The thermal contribution of the overlap of pz orbitals is investigated, which noticeably enhances the thermal transport when compared with the thermal conductivity without considering the overlap effect. For a better understanding of its TE advantages, we find that the low-dimensional charge transport results from strong pz-overlap interactions and the in-plane electronic confinement, by comparing π-stacking carbon nitride derivatives and graphite. This study can provide a guidance to search for high cross-plane TE performance in layered materials.

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Section: Resultsmentioning

confidence: 99%

“…Recent investigations have shown that Cn-BTBTs and bis(dithienothiophene) (BDT) have high ZT along the inter-planar direction due to their low-dimensional charge transport [26,27]. Overall, low ph κ and the special electronic properties make stacking organic semiconductors become promising candidates in TE applications.…”

Section: Introductionmentioning

confidence: 99%

Unexpectedly high cross-plane thermoelectric performance of layered carbon nitrides

Ding

et al. 2019

J. Mater. Chem. A

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“…Interestingly, KZnP exhibits a 'flat-and-dispersive' band character that the valence band is nearly flat along the c axis direction but highly dispersive in the ab plane, while the conduction band is significantly dispersive along all directions. This special band structure has been shown to enhance the thermoelectric performance effectively in Fe 2 YZ full Heusler compounds [11], phonon-glass crystals [12], α-HgS [31], SrTiO 3 [23,36], etc. Obviously, the effective mass of the free carriers in KZnP is highly anisotropic because it is proportional to the inverse of the curvature of the band dispersion, as illustrated in real space in figures 3(b), (c) for holes and electrons, respectively.…”

Section: Electronic Properties and Ab Initio Electron-phonon Scatteringmentioning

confidence: 99%

“…For instance, the power factors 4-5 times larger than PbTe or Bi 2 Te 3 was obtained by engineering the appearance of Fe e g states at the bottom of the conduction bands in Fe 2 YZ full Heusler compounds [11]. Strong band dispersion along only one direction by designing a 'phonon glass-electron crystal' has been proved to be effective to enhance thermoelectric performance [12]. Apparently, coexistence of flat and highly dispersive bands near the Fermi level offers a very promising avenue for exploring materials with desired properties, since a small effective mass in one direction benefits the carrier mobility and hence the electrical conductivity, while a large effective mass along the other direction contributes to an overall large DOS and large Seebeck coefficient.…”

Section: Introductionmentioning

confidence: 99%

Ab initio study on anisotropic thermoelectric transport in ternary pnictide KZnP

et al. 2019

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Strongly anisotropic bands near the Fermi level via band structure engineering have been proposed to enhance thermoelectric performance in functional materials. Recent works exhibit the presence of flat-and-dispersive-band-like strong anisotropy in a class of ternary transition metal pnictides. Taking KZnP as a representative example, here we investigate the thermoelectric properties of this class of materials based on first-principles calculations and semiclassical Boltzmann transport theory. Strikingly, the calculated lattice thermal conductivity k L shows a strong anisotropy with a small value of about 5.24 (2.58) W m −1 K −1 along the in-plane (out-of-plane) lattice direction at room temperature. Based on the electron relaxation time calculated from intensive ab initio electronphonon interactions, a thermoelectric figure of merit zT of 0.32 is predicted for n-type doped KZnP, about two times lower than the value estimated by the constant relaxation time approximation from deformation potential theory. Nanostructures with the characteristic length shorter than 13 nm can reduce the k L by 40%, enhancing zT to 0.52 along the c axis direction. This work supports that KZnP is a potential candidate for thermoelectric applications.

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“…Owing to the increasingly severe energy and environmental crisis, exploration of new renewable and clean energy has aroused [1][2][3] considerable attentions recently. Thermoelectricity, which could potentially convert part of low-grade waste heat into viable electricity, is [3][4][5][6][7][8] one of the pollution free energy conversion approaches. The performance of thermoelectric materials is measured via the 2 dimensionless figure of merit: ZT = S σT/κ.…”

Section: Introductionmentioning

confidence: 99%

Doping Induced Abnormal Contraction and Significant Reduction of Lattice Thermal Conductivity of Open Framework Si24

Ouyang¹,

Liu²,

Chen³

et al. 2018

ES Energy Environ.

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Effectively suppressing lattice thermal conductivity is a critical step for improving the thermoelectric performance. Taking open framework Si , 24 a potential thermoelectric material and a newly synthesized cage-like Si allotrope, as an example, we systematically investigate the lattice thermal conductivity of this new structure filled with alkaline-earth guest atoms (X@Si , X = Mg, Ca, Sr, and Ba) by combining first-principles 24 calculation and phonon Boltzmann transport theory. The calculated lattice thermal conductivity is obviously decreased as guest atoms are inserted in the void sites of the Si framework, which is a common phenomenon for the guest-host systems. However, it is surprising to find that the 24 thermal conductivity of this new filler structure presents a prominent element dependency. Inserting Ca into Si framework generally leads to 3 to 24 10 times lower thermal conductivity than that with other alkaline-earth atom fillers, and the value along zz crystal direction of 0.59 W/mK is even lower than that of amorphous silicon, despite the intrinsic thermal conductivity of pristine Si is as high as 21.25 W/mK. Such ultra-low thermal 24 conductivity is found to be closely related to the strong harmonic interatomic interaction among guest and host atoms of Ca@Si system. The 24 strong interaction gives rise to anomalous contraction effect on the Si lattice (the volume abnormally decreases) and more dispersive phonon 24 branches in low frequency range, which boosts the three-phonon scattering channels (reflected by the weighted phase space) and eventually suppresses the thermal conductivity of Si. Finally, based on a simple and effective lattice chain model, we reproduce the abnormal thermal 24 phenomenon observed in Ca@Si , and further demonstrate that the origin stems from the strong interaction between Ca and Si atoms. These 24 findings shed light on a new physical mechanism for the reduction in thermal conductivity of Ca@Si , which offer a promising approach to 24 improve the thermoelectric efficiency of Si related materials.

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Enhancing the Thermoelectric Figure of Merit by Low-Dimensional Electrical Transport in Phonon-Glass Crystals

Cited by 67 publications

References 59 publications

Unexpectedly high cross-plane thermoelectric performance of layered carbon nitrides

Unexpectedly high cross-plane thermoelectric performance of layered carbon nitrides

Ab initio study on anisotropic thermoelectric transport in ternary pnictide KZnP

Doping Induced Abnormal Contraction and Significant Reduction of Lattice Thermal Conductivity of Open Framework Si24

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