Potential Applications In Thermoelectric Devices Research Articles

Pressure-induced extreme anisotropic behavior of thermoelectric properties in crystalline β-CuSCN

Applying hydrostatic pressure has emerged as a promising strategy for regulating the properties of thermoelectric materials, particularly in the case of β-CuSCN, which has garnered attention due to its ultra-low thermal conductivity and potential applications in thermoelectric devices. Herein, we investigate the intrinsic mechanism governing the electron-thermal transport properties of β-CuSCN under hydrostatic pressure. It was found that ZT decreased by 30 % along the in-plane direction while increasing by 24 % along the out-of-plane direction following the application of hydrostatic pressure, respectively. Our results reveal that the competitive relationship between pressure-driven effects on phonon dynamics and electronic structure influences the thermoelectric properties of β-CuSCN. For the transport mechanism, the compression alters phonon dispersion by enhancing atomic interactions, which leads to an increase in lattice thermal conductivity. On the other hand, despite strong coupling between electrical transport parameters, a net increase in power factor is achieved through pressure-induced bandgap narrowing. As a result, the thermoelectric properties demonstrate contrary variation tendency along the in-plane and out-of-plane directions. Our research deepens our understanding of transport behavior under extreme pressure conditions and provides valuable insights into the fundamental relationship between structural deformation and thermoelectric performance.

Unveiling the thermoelectric, optical and mechanical performances of Hafnium and Zirconium based Beryllium oxide perovskite

The investigated research study includes ab-initio calculations for Beryllium based oxide perovskite namely XBeO3 (X= Zr and Hf). The study aims to comprehend their mechanical, optical, and thermoelectric properties. The density functional theory is used in conjunction with the full potential linearized augmented plane wave method via WIEN2K code to conduct these studies. ZrBeO3 and HfBeO3 both met the mechanical requirements for stability while having an anisotropic character. Mechanical characteristics demonstrate the brittleness of ZrBeO3 and the ductility of HfBeO3. The determined band profile of both materials shows semiconducting behavior with indirect bandgap. Optical properties are performed within photon energy range of 0–12 eV. ZrBeO3 and HfBeO3 are anticipated to have real dielectric function values of 5.45 and 3.75, respectively. The upward trend of absorption coefficient towards higher energies signifies attenuation in light transmittance through the materials making them strong candidate as UV-absorber. The thermoelectric parameters are finally assessed using the BoltzTrap code and their variances with temperature and chemical potential are also presented. ZrBeO3 and HfBeO3 exhibit intriguing thermoelectric characteristics, with TE efficiency values of 0.24 and 0.4, respectively. Additionally, thermoelectric study shows that ZrBeO3 and HfBeO3 are stable at room temperature and have potential applications in thermoelectric devices.

First principle calculation of thermoelectric transport performances of new dual transition metal MXene

The quantum restriction effect of charge carriers in two-dimensional materials can significantly improve their power factors. MXene, as a new type of two-dimensional double transition metal material, has attracted extensive attention due to thermoelectric properties, and higher controllability than single transition metal MXene, which has potential applications in thermoelectric devices. In this work, new two-dimensional monolayer double transition metal MXene, i.e. TiZrCO<sub>2</sub> and VYCO<sub>2</sub>, are designed and their stabilities, electronic and thermoelectric properties are studied by the first principles and Boltzmann transport theory. It has been shown that both are indirect bandgap semiconductors with mechanical, thermodynamic and kinetic stability, and their thermoelectric properties (Seebeck coefficients, electrical and electronic thermal conductivities and lattice thermal conductivities) in a temperature range from 300 K to 900 K are studied. For the optimal carrier concentration at 300 K, the p-type TiZrCO<sub>2</sub> power factor is 11.40 mW/(m·K<sup>2</sup>), much higher than that of n-type one, and the VYCO<sub>2</sub> power factor of p-type (2.80 mW/(m·K<sup>2</sup>)) and n-type (2.20 mW/(m·K<sup>2</sup>)) are similar to each other. At 300 K, TiZrCO<sub>2</sub> and VYCO<sub>2</sub> have low lattice thermal conductivities of 5.08 W/(m·K) and 3.22 W/(m·K), respectively, and the contributions of optical phonon to the lattice thermal conductivity are both about 30%, i.e. 2.14 W/(m·K) and 1.09 W/(m·K) at 900 K, respectively. At the same time, it is found that at 300 K, when the material sizes of TiZrCO<sub>2</sub> and VYCO<sub>2</sub> are within 12.84 nm and 5.47 nm respectively, their lattice thermal conductivities are almost unchanged, and can be adjusted by adjusting the compositions. At 900 K, the thermoelectric value of p-type TiZrCO<sub>2</sub> and VYCO<sub>2</sub> reach 1.83 and 0.93, respectively, which are better than those of n-type, 0.23 and 0.84. The double transition metals MXene TiZrCO<sub>2</sub> and VYCO<sub>2</sub> have better thermoelectric properties than the single transition metal MXene (such as Sc<sub>2</sub>C(OH)<sub>2</sub>, <i>ZT</i> = 0.5), and have the potential applications in new thermoelectric materials with excellent comprehensive properties. A set of calculation methods used in this paper can also provide some reference for exploring the thermoelectric properties of a new double transition metal element MXene.

Exploring the ultra-low lattice thermal conductivity of a two-dimensional compound Tl2Se3

Two-dimensional (2D) materials have attracted extensive attention in the field of thermoelectric (TE) materials, where heat transport properties play an important role in determining the performance of TE devices. In this paper, we investigate the thermal transport properties of novel 2D Tl2Se3 by means of first-principles approach combined with the Boltzmann transport equation (BTE). The small phonon sound group speed and strong anharmonicity are responsible for an ultra-low kl of 0.28 W/mK of 2D Tl2Se3 at room temperature. Meanwhile, the lattice thermal conductivity gradually decreases with the increase of temperature, indicating its potential value at high-temperature. The anti-bonding orbital filling between the Se-4p and Tl-6p states leads to the weak chemical bonds using the crystal orbital Hamiltonian population (COHP) analysis, which results in low phonon group velocities. Also, due to the strong acoustic-optical coupling in 2D Tl2Se3, the scattering processes of different acoustic modes is further studied to analyze how kl is suppressed. These findings demonstrate that 2D Tl2Se3 has potential applications in TE devices, which will motivate Tl2Se3 based experimental investigations.

Microscale Engineering of n-Type Doping in Nanostructured Gallium Antimonide: AC Impedance Spectroscopy Insights on Grain Boundary Characterization and Strategies for Controlled Dopant Distribution.

This paper investigates the microscale engineering aspects of n-type doped GaSb to address the challenges associated with achieving high electrical conductivity and precise dopant distribution in this semiconductor material. AC impedance spectroscopy is employed as a reliable technique to characterize the microstructural and electrical properties of GaSb, providing valuable insights into the impact of grain boundaries on overall electrical performance. The uneven distribution of dopants, caused by diffusion, and the incomplete activation of introduced dopants pose significant obstacles in achieving consistent material properties. To overcome these challenges, a careful selection of alloying elements, such as bismuth, is explored to suppress the formation of native acceptor defects and modulate band structures, thereby influencing the doping and compensator formation processes. Additionally, the paper examines the effect of microwave annealing as a potential solution for enhancing dopant activation, minimizing diffusion, and reducing precipitate formation. Microwave annealing shows promise due to its rapid heating and shorter processing times, making it a viable alternative to traditional annealing methods. The study underscores the need for a stable grain boundary passivation strategy to achieve significant improvements in GaSb material performance. Simple grain size reduction strategies alone do not result in better thermoelectric performance, for example, and increasing the grain boundary area per unit volume exacerbates the issue of free carrier compensation. These findings highlight the complexity of achieving optimal doping in GaSb materials and the importance of innovative analytical techniques and controlled doping processes. The comprehensive exploration of n-type doped GaSb presented in this research provides valuable insights for future advancements in the synthesis and optimization of high-conductivity nanostructured n-type GaSb, with potential applications in thermoelectric devices and other electronic systems.

Two-dimensional Nowotny-Juza NaZnX (X = P, As, Sb) as high-performance thermoelectric materials

Ideal thermoelectric material requires high power factor and low thermal conductivity. Two-dimensional structuring of bulk thermoelectric materials has been reported to be an effective way to achieving excellent thermoelectric performance. In this work, we proposed three two-dimensional Nowotny-Juza materials: NaZnP, NaZnAs, and NaZnSb. Based on the state-of-the-art first-principles calculations, it is revealed that the monolayers possess high stability, low cleavage energy, and excellent electronic transport performance with power factor of 0.65, 0.15 and 0.06 Wm−1K−2 respectively. Meanwhile, the monolayers exhibited ultra-low thermal conductivities of 1.16, 1.38, and 0.31 W⋅m−1⋅K−1 at 300 K, respectively. Such low thermal conductivities are mainly due to the larger scattering rates, resulting from the special cage structure of NaZnX (X = P, As, Sb) and weak ionic bond. As a result, their ZT values reach 2.59, 1.78, and 0.05 (at 300 K), respectively, and increase further to 6.03, 3.23, and 0.13 (at 700 K), respectively. The exceptional performance of NaZnX monolayers sheds light on their immense potential applications in thermoelectric devices.

Insight on structural, electronic and thermoelectric properties of perovskite AgBaCl3 by an Ab-initio for solar cell and renewable energy

The physical properties of the Ag-based perovskite compound AgBaCl3 has been studied utilizing FP-LAPW approach as embedded in WIEN2k code. The PBE-GGA approximation has been considered for the structural optimization. The structural and thermodynamical stability of the studied AgBaCl3 is confirmed from its tolerance factor, formation energy and cohesive energy. The band structure and density of states are estimated for electronic characteristics, proving the semiconductor nature, with indirect band gap values for PBE-GGA of 1.8 eV. The optical characteristics of the AgBaCl3 are studied in terms of the real and imaginary dielectric function, refractive index and reflectivity The thermoelectric properties of the compounds are studied at a temperature range of 0–1200 K with temperature. The high-power factor of the studied compound reveals its potential application in thermoelectric devices.

First-principles calculations to investigate electronic, optical, and thermoelectric properties of Na2GeX3 (X = S, Se, Te) for energy applications

The optoelectronic, structural, and transport properties of the ternary chalcogenides Na2GeX3 (X = S, Se Te) are investigated by the full-potential linearized augmented plane wave (FP-LAPW) method. Na2GeS3 and Na2GeSe3 have a direct bandgap, while Na2GeTe3 is an indirect bandgap material. The magnitude of the bandgap decreases by replacing S with Se and Te. Optical parameters such as dielectric function, refractive index, reflectivity, absorption coefficient, and energy loss function are also calculated to check their potential in optoelectronic applications. The considered chalcogenide compounds may be promising candidates for photovoltaic devices operating in the UV regions due to their high absorption coefficient in these regions.The calculated thermoelectric parameters (electrical and thermal conductivity, Seebeck coefficient, figure of merit, power factor) indicate that the Na2GeX3 chalcogenides are promising for potential applications in thermoelectric devices.

Phonon thermal transport in graphene/h-BN superlattice monolayers

The superlattice monolayers composed of periodically assembled graphene and hexagonal boron nitride (h-BN) superlattices by strong covalent bonds have aroused great interest in academia and industry due to their adjustable physical properties, which are expected to play an important role in the modulation of material properties, especially in thermal transport properties. In general, thermal transport properties highly rely on the characteristic of nanostructures. Thus, understanding the impact of structural characteristics on physical properties is essential for the design of high-performance materials. In this study, we report our results from three different methods including non-equilibrium molecular dynamics, homogeneous non-equilibrium molecular dynamics, and spectral heat current decomposition to explore the phonon thermal transport properties in different graphene/h-BN superlattice monolayers, which are constructed by periodically stitched and equal-sized graphene and h-BN superlattices. We find that the thermal conductivities decrease first and then increase with the increase of periodic length, corresponding to a transition from coherent transport to incoherent transport, and a minimum thermal conductivity at a certain period is identified. These results provide a theoretical validation of a possible control on thermal properties at the nanoscale, which may have potential applications in thermoelectric devices once upon experimental validation.

Thermal conductive thin, flexible composite sheet of boron nitride aggregates and alumina for enhanced through plane conductivity

In electronics sector, the trend of miniaturization will undoubtedly continue to drive forward with several technological advancements, however, there are some crucial issues especially in the thermal management of electronic devices that limits to what is pragmatically and economically feasible. For ensuring efficient thermal dissipation and preventing temperature overloads at local sites, in this work, an advanced thermal filler material (BN aggregate) synthesized via a cost effective and scalable route from h-BN (Hexagonal Boron Nitride) is proposed. To assess the suitability of the BN aggregate as a conventional ceramic filler material and its effectiveness for thermal management, a thermally conductive thin composite sheet is (200 μm) fabricated with the synthesized BN aggregates and spherical Al2O3. The thermal sheet made out of an optimized ratio between the Al2O3 and BN aggregate delivers an excellent through-plane (k⊥) and in-plane (k∥) thermal conductivity of 8.142 W/m.K and 5.601 W/m.K respectively. Even at higher filler concentration, this thin sheet which mimics a papery film, practically endured no deterioration in the mechanical integrity. This thermal sheet given its reasonable thermal and mechanical properties can be employed in electrical devices that demands high power cycles. With wearable technology gaining greater attention in the recent days, the proposed filler system when dispersed in polyethylene fibers, may find potential applications in thermoelectric devices, smart textiles, wearable displays and health monitoring systems.

Phonon transport in Zintl Ba2ZnAs2 and Ba2ZnSb2: A first-principles study

Layered Zintl Ba2ZnX2 (X=As, Sb, and Bi) with intrinsically ultralow lattice thermal conductivity (κ) have attracted continuous attention because of their potential applications in thermoelectric devices. Understanding the low-κ mechanism is favorable for preserving the temperature gradient between the two ends of a material and achieving high thermoelectric performance. Herein, based on first-principles calculations, we systematically report the phonon-limited thermal conductivities of Ba2ZnX2. In the framework of the harmonic approximation, the absence of unstable vibrational modes indicates Ba2ZnAs2 and Ba2ZnSb2 are dynamically stable, while Ba2ZnBi2 is unstable with imaginary frequencies in the phonon dispersion. Remarkably, Ba2ZnSb2 exhibits low acoustic phonon group velocities (<4.5 km/s), large Grüneisen parameters, short phonon relaxation time (<5.5 ps), low-lying optical modes (∼1.5 THz), and strong optical-acoustic phonon couplings. These inherent phonon features can greatly hinder the heat transport ability and therefore give rise to an ultralow thermal conductivity of ∼ 0.11 W/mK at 300 K for Ba2ZnSb2. Furthermore, elastic properties calculated based on the density functional theory helped to gain insight into the origin of the low κ. Our study provides fundamental physical insights into the reason of low thermal conductivity of Ba2ZnX2, which is valuable toward the search for efficient thermoelectric materials based on layered Zintl phase compounds.

Pressure and doping effects on the structural stability of thermoelectric BaAg2Te2

Ternary chalcogenides have attracted great attention for their potential applications in thermoelectric devices. Here, we investigate the pressure and doping effects on the structural stability of BaAg2Te2 using first-principles calculations. Imaginary frequencies are observed in the calculated phonon dispersions of the reported Pnma structure, indicating that Pnma BaAg2Te2 is lattice dynamically unstable at 0 K. Although the imaginary phonon frequencies are small, we find that hydrostatic pressure cannot effectively stabilize the structure. Based on the soft mode at Γ point, a new monoclinic phase with a space group of P21/c is proposed. From ab initio molecular dynamics simulations, the P21/c phase is predicted to transform to the Pnma phase at a low temperature below 100 K. Electron/hole doping effects on the lattice dynamical stability of the Pnma phase are also studied. It is found that hole doping is superior to electron doping in stabilizing the Pnma phase. Further study on the electrical transport properties of the Pnma phase reveals a higher performance along b axis than that along the other two directions. This work paves an avenue to better understand the structural stability and electrical transport properties of thermoelectric BaAg2Te2.

Electronic structure, magnetic, optical and transport properties of half-Heusler alloys RhFeZ(Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) – a DFT study

ABSTRACT The properties such as structural, mechanical, electronic structure, magnetic, optical and transport properties of the half-Heusler alloys of Rhodium RhFeZ(Z = P, As, Sb, Sn, Si, Ge, Ga, In, Al) are investigated at normal pressure. The alloys RhFeSb, RhFeSn, RhFeGe, RhFeGa, RhFeIn and RhFeAl are more stable in γ-phase. But the alloys RhFeP, RhFeAs and RhFeSi exhibit stability in β-phase under normal pressure. Among the investigated alloys, RhFeSn and RhFeGe are half-metallic at normal pressure. All the other half-Heusler alloys, RhFeP, RhFeAs, RhFeSb, RhFeSi, RhFeGa, RhFeIn and RhFeAl are ferromagnetic at normal pressure. To understand the transport properties, Seebeck coefficients, electrical conductivity, thermal conductivity and power factor are examined. The investigation infers that the alloys RhFeSn and RhFeGe possess remarkable transport properties and find potential applications in thermoelectric devices.

Tailoring acoustoelastic, piezoelectric and thermal properties of Janus GeC sheets

The effect of F and H dopants on the structural, elasticothermal and piezoelectric properties of Janus GeC hybrids is studied using ab-initio calculations. The large elastic regions observed reveal a high flexibility of Janus structures. A high rigidity with a hyperelastic softening behavior are observed for this class of materials making them very potential for automotive industry. Configurations where H-atoms decorate C atoms are cork materials. It is also demonstrated that ZA Grüneisen phonon mode are the main responsible of the negative value of thermal expansion. The ultralow thermal conductivity of Janus GeC structures indicate their potential application in thermoelectric devices. Therefore, the strain-engineering of hydro-fluorinated GeC would open a new avenue for potential and novel applications in nano-devices.

Organic Semiconducting Materials Based on BDOPV: Structures, Properties, and Applications

What are the major current research activities of your group?To develop high performance organic semiconducting and conducting materials and also to understand their structure‐property relationships. We are also interested in the effect of the aggregation states of the conjugated polymers on their electronic properties, the doping process and mechanism.What is the most important personality for scientific research?Curiosity and the desire to learn. Meanwhile, one should enjoy and be happy in the process of scientific exploration.Could you please share some experiences with young researchers in starting up their career?Keeping in mind that doing research is never a torturous course but always a process with pleasure, during which your curiosity gets satisfiedand you can better understand about the science under the experiment. Meanwhile, one will get a sense of achievement whenever you solve a problem or overcome the challenge.How do you supervise your students?A supervise should share joys and tears with them, and give them a hand when they need help.What's your hobbies?I enjoy anything that makes me think, like reading. And I prefer cooking.Which kinds of journals do you think are outstanding journals?There is no need for us to evaluate a commercialized journal. One should focus on the research process they are conducting instead of the publications.Organic semiconductors have achieved remarkable development due to their promising applications in low‐cost, lightweight, and flexible electronics. Both n‐type and p‐type semiconductors with comparable performance are necessary for high quality p‐n junctions, complementary circuits. However, compared with their p‐type counterparts, in which the hole mobilities are even up to 40 cm2·V–1·s–1, only few n‐type semiconductors exhibited electron mobilities surpassing 1 cm2·V–1·s–1. Recently, benzodifurandione‐ based oligo(p‐phenylene vinylene) (BDOPV)‐based small molecules and polymers have exhibited outstanding electronic performance and ambient‐stability: the highest electron mobility is up to 14.9 cm2·V–1·s–1. In addition, BDOPV‐based polymers exhibit great potential applications in thermoelectric devices, biomedicine, etc. In this review, we provide a comprehensive insight into BDOPV derivatives from rational design, structure‐property relationships, morphology control, and their applications.

The thermoelectric properties of monolayer SiP and GeP from first-principles calculations

Monolayer silicon phosphide (SiP) and germanium phosphide (GeP) are predicted to exhibit fascinating electronic characters with highly stable structures, which indicate their potential applications in future electronic technologies. By using first-principles calculations combined with the semiclassical Boltzmann transport theory, we systematically investigate the thermoelectric properties of monolayer SiP and GeP. High anisotropy is observed in both phonon and electron transport of monolayer SiP and GeP where the thermal and electrical conductivity along the xx crystal direction are smaller than those along the yy crystal direction. The lattice thermal conductivity (room temperature) along the xx crystal direction is about 11.05 W/mK for monolayer SiP and 9.48 W/mK for monolayer GeP. However, monolayer SiP and GeP possess almost isotropic Seebeck coefficient, and the room temperature values with both n- and p-type doping approach 2.9 mV/K and 2.5 mV/K, respectively. Based on the electron relaxation time estimated from the deformation potential theory, the maximum thermoelectric figure of merit of monolayer SiP and GeP with n-type doping approach 0.76 and 0.78 at 700 K, respectively. The results presented in this work shed light upon the thermoelectric performance of monolayer SiP and GeP and foreshow their potential applications in thermoelectric devices.

New free-standing and flexible PVA/Carbon quantum dots (CQDs) nanocomposite films with promising power factor and thermoelectric power applications

Recently, flexible nanocomposite thermoelectric materials, especially inorganic polymers, have attracted increasing attention. In this paper, we successfully fabricated novel P-type thermoelectric PVA/CQDs nanocomposite films through the solution casting technique. Zero-dimension CQDs nanoparticles were first prepared by the microwave heating method and then injected into the PVA matrix to achieve free-standing films. PVA/CQDs nanocomposite films were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermoelectric properties such as electrical conductivity, Seebeck coefficient, and thermal conductivity of the prepared films were studied. XRD patterns showed the effect of CQDs nanoparticles on the crystallinity of the nanocomposite. The average size of CQDs nanoparticles was found to be 4.5 nm. The PVA/CQDs nanocomposite has a high conductivity (30.3 S/cm), an excellent power factor (15.2 μW/m K2), and a high figure of merit (0.005) with CQDs content of 2 wt%. Finally, these nanocomposites have a promising potential application in thermoelectric devices because they are economical and easy to scale up.

An efficient two-step Monte Carlo method for heat conduction in nanostructures

Research on the heat conduction in nanostructures has drawn much attention due to their potential applications in thermoelectric devices. Although the phonon tracing Monte Carlo (MC) technique, where the trajectories of individual phonons are simulated independently, has been extensively used for simulating the heat conduction in nanomaterials, it cannot efficiently simulate the phonon transport in the large area periodic nanostructures yet, due to the demand of absorbing boundaries. In the present work, we develop a two-step phonon tracing MC method to solve this problem. At the first step, the initial phonon transmittance and the phonon emission distributions at the internal virtual boundary are obtained by simulating phonon transport in the initial simulation unit that is directly in contact with the phonon bath. At the second step, the internal phonon transmittance is calculated for the internal simulation units according to the internal boundary phonon emission distributions. Since the whole structure can be simplified as a one-dimensional phonon transport system, the total phonon transmittance can be readily calculated via the combination of initial and internal phonon transmittances, and the effective thermal conductivity is then derived. Furthermore, for verification, we calculate the effective thermal conductivities of three typical nanostructures, that is, the cross-plane and in-plane nanofilms and the periodic nanoporous structures, by using the theoretical models, the standard and the two-step MC simulations, respectively. The two-step MC method well predicts the results calculated by the standard MC simulations and the theoretical models. More importantly, the computation time of the two-step MC simulation is at least one order of magnitude less than that of the standard MC simulation, while its under-prediction can be less than 10% even 5%.

Thermoelectric properties of orthorhombic group IV–VI monolayers from the first-principles calculations

Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, the thermoelectric properties of orthorhombic group IV–VI monolayers AB (A = Ge and Sn; B = S and Se) are systematically investigated by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is considered for their electron part, which produces observable effects on the power factor, especially for n-type doping. According to the calculated ZT, the four monolayers exhibit diverse anisotropic thermoelectric properties although they have a similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion. This can be explained by the strength of anisotropy of their respective power factor and electronic and lattice thermal conductivities. The calculated results show that the ZT between n- and p-type doping has little difference for GeS, SnS, and SnSe. It is found that GeSe, SnS, and SnSe show better thermoelectric performance compared to GeS in n-type doping and that SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to other many 2D materials, orthorhombic group IV–VI monolayers AB (A = Ge and Sn; B = S and Se) may possess better thermoelectric performance due to lower lattice thermal conductivities. Our work would be beneficial to stimulate further theoretical and experimental works.

High thermoelectric performance of Weyl semimetal TaAs

Abstract The existence of Weyl nodes predicted in TaAs has been confirmed by angle-resolved photoemission spectroscopy, which provides potential applications in thermoelectric devices due to the extraordinary transport properties of TaAs. By using first-principles calculations and semiclassical Boltzmann transport theory, we study the electrical transport properties of TaAs. High anisotropy is observed in the electrical transport of TaAs. The obtained Seebeck coefficients are in good agreement with experimental values. The lattice dynamics properties of TaAs are also investigated and the obtained phonon frequencies agree well with the measurements. The lattice thermal conductivity is calculated using the self-consistent iterative approach. Anisotropic lattice thermal conductivity is observed as well. Maximum thermoelectric figure of merit zT of 0.63 at 900 K is found for n-doping TaAs along zz direction. Finally, the size dependence of lattice thermal conductivity and corresponding thermoelectric properties are investigated for designing thermoelectric nanostructures. The work sheds light on the nature of the thermoelectric response of Weyl semimetal.