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The binary CoSb3 skutterudite thermoelectric material has high thermal conductivity due to the covalent bond between Co and Sb, and the thermoelectric figure of merit, ZT, is very low. The thermal conductivity of CoSb3 materials can be significantly reduced through phonon engineering, such as low-dimensional structure, the introduction of nano second phases, nanointerfaces or nanopores, which greatly improves their ZT values. The phonon engineering can optimize significantly the thermal transport properties of CoSb3-based materials. However, the improvement of the electronic transport properties is not obvious, or even worse. Energy band and charge-carrier engineering can significantly improve the electronic transport properties of CoSb3-based materials while optimizing the thermal transport properties. Therefore, the decoupling of thermal and electronic transport properties of CoSb3-based materials can be realized by energy band and charge-carrier engineering. This review summarizes some methods of optimizing synergistically the electronic and thermal transport properties of CoSb3 materials through the energy band and charge-carrier engineering strategies. Energy band engineering strategies include band convergence or resonant energy levels caused by doping/filling. The charge-carrier engineering strategy includes the optimization of carrier concentration and mobility caused by doping/filling, forming modulation doped structures or introducing nano second phase. These strategies are effective means to improve performance of thermoelectric materials and provide new research ideas of development of high-efficiency thermoelectric materials. [ABSTRACT FROM AUTHOR]

Abstract Interface engineering has prevailed in the thermoelectric field for decades, and related performance has achieved great progress. Therefore, an in‐depth understanding of the impacts of the interface effect on the thermoelectric transport parameters is of vital importance. In this paper, taking skutterudite‐based thermoelectric materials as typical examples, the formation mechanism and preparation process of various interface types, including 1D dislocations, 2D grain refinement, 3D nanocomposites, and micro‐nanopores, are briefly summarized. In addition, we also systemically highlight recently striking achievements related to interfacial design to reveal the distinctive effect of each interface structure on the transport behavior of carriers and phonons. Finally, existing challenges in the thermoelectric performance optimization achieved by interface engineering are pointed out, and an outlook for further thermoelectric research is presented.

The n‐type MNiSn (M = Ti, Zr, or Hf) half‐Heusler compounds are reported as promising medium‐ and high‐temperature thermoelectric materials; however, their p‐type counterparts have suffered from poor performance due to the in‐gap state caused by Ni occupying the tetrahedral interstitials. Inspired by recent findings that thermoelectric performance can be enhanced without substantially increasing compositional or structural complexity, the study attempts to manipulate the Ni interstitial defects by altering the stoichiometric composition. The results show that when HfNiSn is prepared by a non‐equilibrium method, the intrinsic Ni defects are effectively suppressed by simply reducing the nominal Ni content. The suppression of Ni defects not only leads to a larger bandgap, but also attenuates carrier scattering to achieve higher mobility. After further optimization of the carrier concentration, the p‐type HfNi0.85Co0.05Sn achieves a maximum power factor of 3100 µW m−1 K−2 at 773 K and a peak zT of ≈0.7 at 973 K, both of which are superior to that of the state‐of‐the‐art p‐type MNiSn. The results demonstrate that the off‐stoichiometric ratio is effective in decoupling electron‐phonon transports of thermoelectric materials with massive intrinsic defects, and also contribute to understanding the role of defect modulation in optimizing thermoelectric properties. [ABSTRACT FROM AUTHOR]

SnSe is a very strong anisotropic material; sometimes, strong anisotropy is unenviable for producing parts of thermoelectric (TE) devices. In order to study the efficient preparation of high-performance n-type polycrystalline SnSe with weak anisotropy, in this work, we combine mechanical alloying at 450 RPM for 10 h and spark plasma sintering at 773 K under 50 MPa pressure for the preparation of polycrystalline SnSe 0.95- x I x (x = 0,0.01,0.02,0.03) samples, and investigate the TE properties. The prepared samples show very weak anisotropy. With iodine doping, increased carrier concentration is observed, in agreement with DFT calculations. A peak ZT ≈ 1.02 at 723 K is observed with I-doping of x = 0.02, which is about 225% higher than that of undoped sample with ZT ≈ 0.31 at 723 K in parallel direction, mainly attributed to the enhanced power factor and about 56% reduced thermal conductivity from 0.68 Wm−1K−1 to 0.30 Wm−1K−1. TE properties in both directions are not much different, and the ratios of electrical and thermal conductivities in both directions are very close to unity. [ABSTRACT FROM AUTHOR]

Donor-doped SrNb 2 O 6 -based materials are regarded as highly promising candidates for high-temperature thermoelectric applications. The Sr 0.6 La 0.4 Nb 2 O 6-δ /x wt% Ti (x = 1, 5, 10, 15) composite ceramics thermoelectric materials were prepared and the mechanism for enhancing their thermoelectric properties was investigated. The experimental results demonstrate that during sintering, nano-additive titanium powder undergoes oxidation to form TiO 2. The inclusion of a secondary phase ultimately leads to successful reduction in electrical resistivity within the composite oxides. Due to crystal defects, complex structure and phonon scattering at grain boundaries, the samples consistently exhibit low thermal conductivity values below 3.0 W m−1K−1. Among them, the sample doped with 10 wt% Ti shows the highest PF value (470.0 μW/mK2 at 1073 K), demonstrating a significant increase in power factor of 280 % compared to Sr 0.6 La 0.4 Nb 2 O 6 without the Ti composite. Consequently, the Sr 0.6 La 0.4 Nb 2 O 6-δ /10 wt% Ti composite material achieved a maximum ZT value of 0.20, representing a fifty-three percent enhancement compared to the undoped sample. [ABSTRACT FROM AUTHOR]

The performance of high-temperature thermoelectric material CaMnO 3 is primarily limited by its high electrical resistivity and thermal conductivity. In this study, we synergistically optimized its electrical and thermal transport properties by employing a combination of doping and compositing strategies. The results suggest that Yb doping promotes the transfer of electrons to the Mn d orbital and facilitates the double exchange interactions between neighbor Mn3+ and Mn4+, leading to decreased electrical resistivity and a transition of electron transport mechanism from semiconductor to metal. The further addition of CoAl 2 O 4 nanoparticles improves the Seebeck coefficient by reducing carrier concentration and increasing electron scattering, ultimately enhancing the power factor. Meanwhile, the fluctuations in atomic mass and increased interface density strengthen the interface phonon scattering, which results in a significant reduction in lattice thermal conductivity. As a result, the Ca 0.95 Yb 0.05 MnO 3 with 2 wt % CoAl 2 O 4 nanoparticles exhibits a maximum ZT value of 0.12 at 850 K, representing a 180 % improvement compared to the pristine material. This study highlights the effectiveness of the combined doping and compositing strategy in enhancing the thermoelectric performance of CaMnO 3 materials and offers a promising approach for optimizing other oxide thermoelectric materials. [ABSTRACT FROM AUTHOR]

Bi2Te3-based alloys are only commercial thermoelectric materials. While, currently, n-type Bi2Te 2. 7 Se 0. 3 -based alloys commonly have lower ZT values than those of p-type Bi 0. 5 Sb 1. 5 Te3 based alloys. In this paper, the influence of different amounts of dispersing honey on the thermoelectric performance of n-type Bi2Te 2. 7 Se 0. 3 alloys synthesized by the hydrothermal and hot-pressing methods was investigated. The carbon atoms contained in honey could increase lattice defects and grain boundary density effectively, and improved the Seebeck coefficient and suppress lattice thermal conductivity simultaneously. By adjusting the amount of honey, the maximum ZT value reached 0.82 at 423 K, which was approximately 65% higher than that of the pristine Bi2Te2.7Se0.3. [ABSTRACT FROM AUTHOR]

The structural, mechanical, and thermoelectric properties of quaternary CuCoZrZ (Z = Sn, Pb) Heusler compounds are theoretically investigated. Both compounds are mechanically and dynamically stable. The indirect semiconductor bandgaps of 0.220 eV for CuCoZrSn and 0.197 eV for CuCoZrPb are observed using the Tran and Blaha‐modified Becke–Johnson technique. The lattice thermal conductivities, calculated by the Slack approach, are 4.69 and 6.90 W mK−1 for CuCoZrSn and CuCoZrPb at 300 K, respectively. The relationship between thermoelectric properties and carrier concentration is studied using the BoltzTrap code. Both n‐ and p‐type CuCoZrZ (Z = Sn, Pb) compounds exhibit high ZT values, making them promising thermoelectric materials. [ABSTRACT FROM AUTHOR]

Cu2Se is an attractive thermoelectric material due to its layered structure, low cost, environmental compatibility, and non-toxicity. These traits make it a promising replacement for conventional thermoelectric materials in large-scale applications. This study focuses on preparing Cu2Se flexible thin films through in situ magnetron sputtering technology while carefully optimizing key preparation parameters, and explores the physical mechanism of thermoelectric property enhancement, especially the power factor. The films are deposited onto flexible polyimide substrates. Experimental findings demonstrate that films grown at a base temperature of 200 °C exhibit favorable performance. Furthermore, annealing heat treatment effectively regulates the Cu element content in the film samples, which reduces carrier concentration and enhances the Seebeck coefficient, ultimately improving the power factor of the materials. Compared to the unannealed samples, the sample annealed at 300 °C exhibited a significant increase in room temperature Seebeck coefficient, rising from 9.13 μVK−1 to 26.73 μVK−1. Concurrently, the power factor improved from 0.33 μWcm−1K−2 to 1.43 μWcm−1K−2. [ABSTRACT FROM AUTHOR]

Thermoelectric materials are widely used in refrigeration chips, thermal power generation, catalysis and other fields. Mg3Bi2-based thermoelectric material is one of the most promising thermoelectric materials. Herein, the Mg3Bi2-based samples were prepared by high temperature synthesis, and the influence of Mg/Sb content on the electrical transport properties and semi-conductivity/semi-metallicity of the materials has been studied. The results indicate that the efficiency of introducing electrons from excess Mg prepared by high temperature synthesis is lower than that introduced by ball milling, due to the high vapor pressure of Mg. The doping of Sb/Te at the Bi site would make it easier for the material to change from p-type conduction to n-type conduction. With the increase in Mg content, the semi-conductivity of the material becomes weaker, the semi-metallicity becomes stronger, and the corresponding conductivity increases. With the increase in Sb content, the samples exhibit the opposite changes. The highest power factor of ~1.98 mWm−1K−2 is obtained from the Mg3.55Bi1.27Sb0.7Te0.03 sample.

Thermoelectric materials should be highly efficient and mechanically robust to satisfy the requirements of engineering applications. Herein, an integrated optimization strategy to improve both the thermoelectric performance and mechanical strength of SnTe is proposed. First, grain boundary engineering is applied to SnTe via MgB2 doping. The decomposition of MgB2 results in the Mg‐substituted SnTe solid solution and a special "core–shell" structure of Mg‐B compounds coated SnTe grain remarkably reducing the lattice thermal conductivity. Subsequently, trivalent Sb atoms are introduced to tune the carrier concentration and optimize the electrical performance of the MgB2‐doped sample. Sb‐rich Sn‐Te precipitates inside the grains further diminish the lattice's thermal conductivity. Consequently, a prominent improvement in average ZT of ≈117% is achieved for Sn0.78Sb0.16Te(MgB2)0.09 compared to pristine Sn1.03Te. Moreover, the compressive yield strength and Vickers hardness of Sn0.78Sb0.16Te(MgB2)0.09 are significantly increased by ≈168% and 176% relative to pristine Sn1.03Te, respectively. The quantitative strengthening models including grain boundary, dislocation, solid solution, intergranular, and precipitation strengthening in MgB2‐ and MgB2‐Sb‐doped Sn1.03Te samples are proposed, showing that the dominant strengthening mechanism is precipitation strengthening. This work provides an avenue for designing efficient and robust thermoelectric materials toward commercial application. [ABSTRACT FROM AUTHOR]

Since the n-type conduction was first discovered, the non-toxic and low-cost Mg3Sb2-based thermoelectric materials have been intensively studied, and likely to become alternative ones to the only large-scale commercialized Bi2Te3-based thermoelectric compounds. This review covers the principle of the mutual conversion of heat and electricity, crystal structure, electronic structure, and p/n-type thermoelectric properties of Mg3Sb2-based materials. Besides, the optimization strategies and underlying mechanisms for improving thermoelectric performance of Mg3Sb2 compounds are briefly analyzed, such as doping, alloying, grain size regulation, and energy band structure design, together with their effects on carrier concentration, carrier scattering, mobility, and Seebeck coefficient. Finally, preliminary research results of Mg3Sb2-based thermoelectric materials applied to power generation and refrigeration, along with the problems related to the future module application, are also discussed.

Here we report the study temperature dependencies of the Seebeck coefficient, the electrical resistivity (T = 300–750 K), the total thermal conductivity (T = 300–973 K), and the thermoelectric figure of merit (T = 300–750 K) of ceramic samples of γ‐Ln0.8Yb0.2S1.5‐y (Ln = Gd, Dy) solid solutions. It was found that Yb3+ ions in γ‐Ln0.8Yb0.2S1.5‐y act as the promoters of higher crystallite nucleation rate during the formation of solid solutions. This results in the sample dispersion increase and the formation of the additional phonon scattering centers (dislocations and strain stresses along the crystallites semi‐coherent boundaries). These features of the real structure determined the low value of thermal conductivity of γ‐Ln0.8Yb0.2S1.5‐y solid solutions. The lowest electrical resistivity 20 μΩ m at 750 K and the thermal conductivity 0.58 W/m K at 973 K, the highest Seebeck coefficient 125 μV/K at 700 K and the maximum thermoelectric efficiency, ZT = 0.60 (at 770 K) were obtained for γ‐Dy0.8Yb0.2S1.5‐y. [ABSTRACT FROM AUTHOR]

Cu 3 SbSe 4 is recognized for its abundant elemental availability, cost-effectiveness, and non-toxic properties, making it a promising candidate for thermoelectric applications at medium temperatures. This study explored the preparation of Bi/Fe, Ag/Fe, and Ag/Bi double-doped Cu 3 SbSe 4 ceramics using vacuum melting and cold isostatic pressing techniques. The focus was on examining the influence of these dopants on the microstructural and thermoelectric performances of Cu 3 SbSe 4. The analysis revealed the presence of Cu 3 SbSe 4 and Cu 2− x Se phases in the doped samples. Double doping optimized the carrier concentration, increased the effective mass, and significantly enhanced the electrical conductivity from 12.45 to 64.01 S cm−1. Notably, the power factor of the Cu 2.85 Ag 0.15 Sb 0.985 Bi 0.015 Se 4 sample reached 649.1 μWm−1K−2 at 573 K. Furthermore, the thermal conductivity was significantly reduced to 0.73 W/mK. The maximum ZT value of the Cu 2.85 Ag 0.15 Sb 0.985 Bi 0.015 Se 4 sample was 0.47 at 573 K. These breakthrough results demonstrate that dual doping markedly enhances the thermoelectric properties of the Cu 3 SbSe 4 system. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of monolayered MnBi2Te4 are investigated using first‐principles calculations based on density functional theory (DFT) and Boltzmann transport theory. Our research indicates significant thermoelectric performance in monolayered MnBi2Te4, with a maximum figure of merit (zT$zT$) and power factor (PF${\mathrm{PF}}$) ranging from approximately 3.58 to 9.267 and 0.012 W/K2m${\mathrm{W}}/{\mathrm{K}}^2{\mathrm{\ m}}$ to 0.021 W/K2m${\mathrm{W}}/{\mathrm{K}}^2{\mathrm{\ m}}$ across a temperature range of 300–700 K. The exceptional thermoelectric performance of monolayered MnBi2Te4 can be attributed to its unique structural and electronic properties, which lead to ultralow lattice thermal conductivity and high electrical transport properties. Ultralow lattice thermal conductivity as low as 0.32W/mK$0.32\ {\mathrm{W}}/{\mathrm{m\ K}}$ at 300 K is found in the monolayered MnBi2Te4, which is mainly contributed from the anharmonic scatterings of low‐frequency phonons. And high electronic conductivity and a notable Seebeck coefficient are also observed in our system, which has close relationship with its distinctive electronic band structure. Besides, the two‐dimensional structure makes it a great candidate to holding greater PF by enhancing the quantum confinement. Our findings may lay a strong theoretical groundwork for future experimental inquiries. Subsequent experimental investigations will be crucial to confirm these findings, refine synthesis methods, and explore the practical applications of monolayered MnBi2Te4 in thermoelectric devices. [ABSTRACT FROM AUTHOR]

Fabricating a thermo‐electro‐magnetic material that exhibits simultaneously excellent magnetocaloric (MC) and thermoelectric (TE) performance is challenging since the interfacial reaction causes severe deterioration of MC and TE performance. In this work, a construction of multi‐scale interfaces in LaFe10.4Co0.8Si1.8/Bi0.5Sb1.5Te3 (LFS/BST) composites is realized by adopting a low‐temperature high‐pressure sintering strategy. It is revealed in the atomic‐scale that the interfacial reaction between LFS and BST leads to the formation of (Fe,Co)(Sb,Te)2 micro‐grains and LaTe2 nano‐grains, and the latter form low‐mismatch phase boundaries with LFS matrix. Benefiting from the multi‐scale interfacial phases, excellent MC performance of LFS is preserved alongside a minor impact on TE properties, e.g., a peak zT of 1.04 and a small decrease of 3.0% in relative cooling power are achieved in the 2%LFS/BST composite. Compared with other thermo‐electro‐magnetic materials, a good trade‐off between MC and TE performance is realized in LFS/BST composites with simultaneously high MC and TE performance. The 20%LFS/BST composite exhibits a room‐temperature zT of 0.46 with large maximum magnetic entropy change and relative cooling power of 0.81 J kg−1 K−1 and 44.83 J kg−1, respectively. This work provides an effective material design for developing the all‐solid‐state MC/TE hybrid refrigeration technique. [ABSTRACT FROM AUTHOR]

The current investigation employs first‐principles DFT (density functional theory) calculations to examine the influence of transition metal replacements on the structural, thermodynamic, and thermoelectric properties of Cu‐based chalcogenides TMCu3Se4 (TM = Nb/Ta/V). The PBE‐generalized gradient approximation (GGA) model is utilized to compute the fundamental properties of Cu‐based chalcogenides under study. A thorough examination of the energy band structures indicates that these chalcogenides are semiconductor compounds with indirect energy bandgaps. We can infer from the calculated energy band structures that the bandgap values are 1.67, 1.77, and 1.05 eV for NbCu3Se4, TaCu3Se4, and VCu3Se4, respectively. The ZTe$$ {\mathrm{ZT}}_e $$ values for NbCu3Se4, TaCu3Se4, and VCu3Se4 are 0.661, 0.998, and 0.996, respectively. These values make them highly appropriate for usage in thermoelectric (TE) devices. The thermoelectric characteristics of pyrochlore oxides TMCu3Se4 (TM = Nb/Ta/V) suggest that these materials have promising potential for energy‐related applications. The analyzed thermodynamic properties demonstrate that the Cu0based chalcogenide materials TMCu3Se4 (TM = Nb/Ta/V) exhibit a notable level of thermal stability. [ABSTRACT FROM AUTHOR]

The structural, electronic, elastic, thermoelectric and optical properties of CeBO3 (B = Be, Mg) oxide perovskites were investigated using density functional theory. Exchange and correlation effects were addressed through the GGA approximation and the TB-mBJ potential. Thermodynamic stability was confirmed by assessing cohesive energy and formation enthalpy. The band structures reveal a semiconductor nature with a moderate indirect band gap of 0.73 (CeBeO3) and 0.51 (CeMgO3). The TB-mBJ approximation has enhanced the gap value with a 55% approaching rate. These compounds exhibited a rigid and elastically anisotropic behavior with chemical bonds manifesting as a mixture of metallic and covalent types. The CeBeO3 displayed ductility while CeMgO3 exhibited brittleness. The optical examination suggests that these oxides exhibit activity across a broad range of the electromagnetic spectrum. Their strong reflectivity in the near-infrared region was particularly noteworthy suggesting potential use as effective shields in this domain. The replacement of beryllium with a magnesium atom enhanced thermoelectric performance by reducing thermal conductivity and increasing the merit factor. Based on the obtained results, the semiconductor perovskites CeBeO3 and CeMgO3 hold promise for efficient applications in optical and thermoelectric devices. [ABSTRACT FROM AUTHOR]

Rare‐earth ternary materials are distinguished by their tunable optoelectronic characteristics and high thermal stability. First principles computations examine the intricate interaction of novel rare‐earth‐based ternary chalcogenide's electronic, optical, and thermoelectric properties. The spin‐down channel of PrHSe exhibits a substantial energy gap resulting in half‐metallic behavior. The f orbitals of Pr and Er play an important role in forming bonds with Se and H atoms, contributing significantly to the valence band. The preponderance of Pr‐f and Er‐f orbitals near the top of the valence band indicate that electrons in these orbitals are the most energetic and participate in bonding interactions within these materials. The ErHSe has a greater absorption rate than PrHSe, and both materials behave isotropically in the xx and zz directions. The highest peaks of the reflection coefficient (50%–70%) in the 1.0–13.8 eV range suggested a significant level of UV reflectivity. The PrHSe has a higher intrinsic carrier concentration for conduction than ErHSe. At lower temperatures, carrier concentrations increase due to thermal activation processes, improving the Seebeck coefficient in these materials. [ABSTRACT FROM AUTHOR]

In this study, we successfully synthesized a series of CuCr0.85Mg(0.15-x)ZnxO2 (x = 0.00 − 0.05) delafossite materials with different Zn concentrations and investigated their thermoelectric properties. Delafossite materials are promising for thermoelectric applications due to their low thermal conductivity and high Seebeck coefficient. We observed that Zn doping significantly affects the structural properties and thermal conductivity of delafossite materials. Zn atoms can substitute for Cr and Cu atoms in the delafossite structure, leading to carrier concentration and mobility changes. We found that the optimal Zn concentration for enhancing the thermoelectric performance is x = 0.0125 − 0.025, which reduces the thermal conductivity from 5.6 to 4.7 W/mK without significantly compromising the electrical conductivity, improving the fi g ure of merit (ZT). The enhancement of ZT at x = 0.0125 is attributed to a high power factor of 220 μW/mK2 resulting from an electrical conductivity of 14.5 S/cm and a Seebeck coefficient of 390 μV/K. This indicates that Zn doping can effectively scatter phonons and improve the ZT of the delafossite materials. [ABSTRACT FROM AUTHOR]

Chromium nitride (CrN) ceramics were sintered at various temperatures by plasma activated sintering, and their thermoelectric properties were explored. The formation of Cr 2 N phase can be suppressed by venting N 2 gas into the chamber before sintering and increasing the sintering temperature to accelerate the densification process. Sintering temperature significantly impacted the thermoelectric properties. Higher sintering temperature led to an increase in the N content, reducing the electrical and thermal conductivity, and increasing the Seebeck coefficient. The single-phased CrN ceramic sintered at 1573 K exhibited excellent thermoelectric performance with a maximum power factor of 1002 μW·m−1·K−2, a thermal conductivity of 4.78 W·m−1·K−1, and a zT value of 0.20 at 973 K. Furthermore, this CrN ceramic also exhibited a high relative density of 97 % and a hardness of ∼11.9 GPa. Enhanced high-temperature thermoelectric properties and excellent mechanical properties make CrN ceramics suitable for thermoelectric applications in extreme environments. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT) combined with semi‐classical Boltzmann transport theory, the electronic and thermoelectric properties of binary skutterudite CoAs3 material are investigated up to 30 GPa. Elastic properties calculations confirm the mechanical stability at 0 GPa and under varying hydrostatic pressures, with ductility influenced by pressure. To ensure dynamical stability, the phonon dispersion frequencies are computed at both 0 and 30 GPa. Electronic band structure calculations, using the GGA + TB‐mBJ approximation, indicate that CoAs3 initially exhibits a direct band gap at its equilibrium lattice constant, which shifts to become indirect under increasing pressure. To assess the impact of pressure on the thermoelectric properties of CoAs3, the Seebeck coefficient, thermal conductivities, and figure of merit (ZT) are calculated at pressures of 5, 10, 20, and 30 GPa for various temperatures (300, 600, 900, and 1200 K). These computations provide valuable insights into how varying pressures influence the material's thermoelectric performance. The optimal thermoelectric properties in CoAs3 material are achieved at 5 GPa and 1200 K for n‐doping (20 GPa and 600 K for p‐doping), with an ideal doping concentration of 1.5 × 1021 cm−3 (5.5 × 1018 cm−3). Under these conditions, the material reaches a high figure of merit (ZT) value of 0.52 for n‐doping and 0.49 for p‐doping. These findings underscore CoAs3 as a promising candidate for applications in energy harvesting and optoelectronic systems, showcasing its robust thermoelectric performance under precise pressure and temperature conditions. [ABSTRACT FROM AUTHOR]

The research on two-dimensional materials has gained significant traction due to their potential for thermoelectric, optical, and other properties. The development of two-dimensional (2D) nanostructured-based TE generators and photodetectors has shown promising results. Over the years, researchers have played a crucial role in advancing this field, enhancing the properties of 2D materials through techniques such as doping, alloying, and various growth methods. Among these materials, black phosphorus, transition metal dichalcogenides, graphene, and IVA-VIA compounds stand out for their remarkable electronic, mechanical, and optical properties. This study presents a comprehensive review of the progress in the field, focusing on IVA-VIA compounds and their applications in TE and photodetector technologies. We summarize recent advancements in enhancing these materials' TE and optical properties and provide an overview of various synthesis techniques for their fabrication. Additionally, we highlight their potential applications as photodetectors in the infrared spectrum. This comprehensive review aims to equip researchers with a deep understanding of the TE and optical properties of 2DMs and their potential applications and to inspire further advancements in this field of research. [ABSTRACT FROM AUTHOR]

Zintl phases typically exhibit low lattice thermal conductivity, which are extensively investigated as promising thermoelectric candidates. While the significance of Zintl anionic frameworks in electronic transport properties is widely recognized, their roles in thermal transport properties have often been overlooked. This study delves into KCdSb as a representative case, where the [CdSb4/4]− tetrahedrons not only impact charge transfer but also phonon transport. The phonon velocity and mean free path, are heavily influenced by the bonding distance and strength of the Zintl anions Cd and Sb, considering the three acoustic branches arising from their vibrations. Furthermore, the weakly bound Zintl cation K exhibits localized vibration behaviors, resulting in strong coupling between the high‐lying acoustic branch and the low‐lying optical branch, further impeding phonon diffusion. The calculations reveal that grain boundaries also contribute to the low lattice thermal conductivity of KCdSb through medium‐frequency phonon scattering. These combined factors create a glass‐like thermal transport behavior, which is advantageous for improving the thermoelectric merit of zT. Notably, a maximum zT of 0.6 is achieved for K0.84Na0.16CdSb at 712 K. The study offers both intrinsic and extrinsic strategies for developing high‐efficiency thermoelectric Zintl materials with extremely low lattice thermal conductivity. [ABSTRACT FROM AUTHOR]

In this manuscript, structural, electronic, optical and thermoelectric properties of chloride perovskites LiMCl3 (M = Pb or Sn) have been studied using Density Functional Theory (DFT) implemented in ABINIT code. The exchange–correlation functionals is treated with Generalized Gradient Approximation of Perdew Burke Ernzerhof (GGA-PBE). Structural properties revealed that the equilibrium lattice parameters for LiPbCl3 and LiSnCl3 are 5.686 and 5.597 Å respectively. These values were used to investigate the thermodynamic stability of these materials by evaluating the energy of formation. The negative formation energy results suggest that the synthesis of LiPbCl3 and LiSnCl3 perovskites is feasible. Further, electronic properties revealed that LiMCl3 (M = Pb and Sn) perovskites are semiconductors with indirect band gaps of 1.87 and 0.98 eV for LiPbCl3 and LiSnCl3, respectively. From the optical properties, we found that the studied materials have a high absorption coefficient, greater than 104 cm−1 in the visible region, indicating their suitability as photovoltaic absorber materials. The results of the elastic properties show that both perovskites are stable and possess ductile behavior. In addition, thermoelectric properties of LiMCl3 (M = Pb and Sn) have been calculated and analyzed using the combination of electronic structure and Boltzmann transport theory. The thermoelectric efficiency results suggest that LiPbCl3 and LiSnCl3 could be potential candidates for thermoelectric devices for high-temperature applications. [ABSTRACT FROM AUTHOR]

A comprehensive theoretical study has been carried out to examine the electronic and thermoelectric properties of As X Y (where X = S , Se; Y = Cl , Br, and I) monolayers. The lattice constants of these monolayers are optimized to determine their most stable configurations. The electronic and thermoelectric characteristics of these monolayers are calculated using state-of-the-art computational methods. Specifically, the first-principles calculations in combination with semiclassical Boltzmann transport theory were employed to gain insights into their behavior. One of the crucial findings of the study is the observation of an indirect band nature in all the studied monolayers. This characteristic provides valuable information about the materials' electronic behavior and potential applications. Furthermore, the impacts of tensile and compressive strains on these monolayers are investigated. Interestingly, we observed changes in the band value when strain is applied, which opens up exciting possibilities for engineering their electronic properties. Importantly, despite these changes, the band nature of the monolayers remains consistent. In particular, it is found that the AsSI monolayer exhibits a remarkable enhancement in the Seebeck coefficient, both in the unstrained state and under a compressive strain of 4% in the p-type region. This enhancement leads to a higher power factor (PF), suggesting that AsSI monolayers could be promising candidates for efficient thermoelectric devices. Overall, these findings highlight the potential of strain engineering to tailor the electronic properties of As X Y monolayers, offering exciting opportunities for their application in thermoelectric devices. This research contributes valuable insights into the design and optimization of novel materials for future energy conversion and electronic applications. [ABSTRACT FROM AUTHOR]

Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) has recently gained interest as a potential candidate for small-scale thermoelectric conversion because of the facile doping, solution processability, and flexibility. However, the practical applications of PEDOT:PSS are limited by its comparatively low figure of merit (ZT) compared with inorganic thermoelectric materials. Herein, to further improve the thermoelectric properties of PEDOT:PSS, we investigated the role of the addition of surfactants, sodium dodecyl sulfate, sodium dodecyl benzenesulfonate (SDBS) or Triton X-100, to the PEDOT:PSS free-standing films on their thermoelectric properties. We showed that the addition of the surfactant improved the film crystallinity, significantly improving the electrical conductivity. The highest conductivity was obtained for anionic surfactant SDBS at a 0.94 wt% concentration. Moreover, the inclusion of the surfactant reduced the thermal conductivity while maintaining a relatively constant Seebeck coefficient, consequently improving the ZT value. Furthermore, a flexible thermoelectric device crafted from the as-fabricated PEDOT:PSS/SDBS sheets was developed to explore the potential applications of wearable electronics using low-grade thermal energy. Overall, we indicate the significance of surfactants in enhancing the thermoelectric properties of free-standing PEDOT:PSS films in this study. [ABSTRACT FROM AUTHOR]

PEDOT:Tos, a PSS-free PEDOT-based material, is a promising possible organic thermoelectric material for a practical conversion module because the material reportedly has a large power factor. However, since PEDOT:Tos is mainly reported to be a p-type thermoelectric material, the development of PSS-free PEDOT with n-type thermoelectric properties is desirable. Thus, in order to search for PSS-free PEDOT with n-type thermoelectric properties, we investigated the doping concentration of PTSA dependence of the thermoelectric property using the first-principle calculation. The band structure and the density of state indicated that the n-type thermal electromotive force was attributed to the electrons’ large effective mass. Such electrons were produced thanks to the binding of the dopant PTSA to the benzene ring. The contribution of the electron to the Seebeck coefficient increased with increasing PTSA doping concentrations.

GeTe is a very promising thermoelectric material, but the presence of massive intrinsic Ge vacancies leads to an overhigh hole concentration and poor thermal stability. Counter doping is commonly employed to reduce the hole concentration, which, however, unavoidably deteriorates the carrier mobility. Here, it is found that the intrinsic hole concentration in the rhombohedral phase is much lower than that in the cubic phase, owing to the higher formation energy of Ge vacancy in the former. With this recognition, the hole concentration of GeTe can be tuned to its optimum value simply by annealing below the phase transition temperature. As a result, "compositional plainification" is realized in the high‐performance GeTe‐based thermoelectrics with significantly reduced amounts of counter dopants and hetero‐alloys. A high carrier mobility of 150 cm2 V−1 s−1 is realized in GeTe at 300 K, which is much higher than that in conventional counter‐doped ones (≤60 cm2 V−1 s−1). More importantly, GeTe‐based compounds, with suppressed intrinsic vacancies, exhibit good thermal stability and reproducibility of thermoelectric performance. A high peak figure of merit, zT, of 2.14 at 670 K is obtained in Ge0.93Bi0.03Pb0.04Te. This work highlights the importance of understanding and regulating the intrinsic vacancy for high‐performance GeTe thermoelectrics. [ABSTRACT FROM AUTHOR]

In this study, SnO wrap on SnS was prepared and incorporated into carbon fiber/expanded graphite (CF/EG) cementitious composites by the coating process. The effects of different SnO wrap on SnS coating ratios and contents on the microstructures of CF/EG cementitious composites were investigated and discussed, and the thermoelectric properties of SnO wrap on SnS CF/EG cementitious composites were systematically investigated in the temperature range of 35–70 °C. The results show that the coating ratio and content of SnO wrap on SnS have a significant effect on the thermoelectric properties of CF/EG cementitious composites. It is noteworthy that when the SnO wrap on SnS is 2:1, the thermoelectric properties of its cementitious composites are greatly improved. For example, when it is added at 1.0 wt%, the conductivity is 2.27 S/cm, the Seebeck coefficient is 41.90 µV/°C and the power factor is 0.38 µW·m−1K−2. The addition of SnO wrap on SnS to CF/EG cementitious materials generates a large number of interfaces, and the presence of high-density interfaces hinders the motion of carriers, which leads to the scattering of carriers at the interfaces and enhances the Seebeck effect in cementitious composites. Therefore, SnO wrap on SnS has great potential for thermoelectric applications. [ABSTRACT FROM AUTHOR]

The demands for waste heat energy recovery from industrial production, solar energy, and electronic devices have resulted in increasing attention being focused on thermoelectric materials. Over the past two decades, significant progress is achieved in inorganic thermoelectric materials. In addition, with the proliferation of wireless mobile devices, economical, efficient, lightweight, and bio‐friendly organic thermoelectric (OTE) materials have gradually become promising candidates for thermoelectric devices used in room‐temperature environments. With the development of experimental measurement techniques, the manufacturing for nanoscale thermoelectric devices has become possible. A large number of studies have demonstrated the excellent performance of nanoscale thermoelectric devices, and further improvement of their thermoelectric conversion efficiency is expected to have a significant impact on global energy consumption. Here, the development of experimental measurement methods, theoretical models, and performance modulation for nanoscale OTE materials are summarized. Suggestions and prospects for the future development of these devices are also provided. [ABSTRACT FROM AUTHOR]

Over the years, Bi2Te3-based alloys have garnered considerable recognition as exceptional thermoelectric materials. Researchers have diligently pursued avenues to enhance the properties of these materials, with a primary focus on reducing thermal conductivity while maintaining optimal electrical performance. Nonetheless, achieving this delicate balance has proven to be a formidable challenge. In this study, we present a novel synergistic optimization approach that entails manipulating the grain refinement and porous structure of the material through precise adjustments in cooling rate and relief temperature during the direct current hot pressing process. By meticulously controlling these parameters, we successfully engineered a multiscale microstructure that effectively promotes phonon scattering. Simultaneously, we optimized carrier concentration. The outcomes of our investigation are truly remarkable, as we attained a peak zT value of approximately 1.23 at 325 K, accompanied by an outstanding average zTave of approximately 1.2 across the temperature range of 300–400 K in the 6.5% porosity-Bi0.35Sb1.65Te3 sample. These findings underscore the efficacy of the multiple synergies employed in our study. Moreover, our research provides a solid foundation for further exploration of complex micro structure modification techniques. [ABSTRACT FROM AUTHOR]

In the current study, the electronic, optical, thermoelectric, and Structural properties of Mg 1−x Zn x O composition have been investigated. The density of states of MgO showed the predominant contribution of Mg- s and O- p orbitals, while for Zn-doped MgO, density of states spectra exhibited strong hybridization among O- p , Mg- s , and Zn- d orbitals. The reduction in band gap with the increase of Zn doping in the MgO host matrix was observed. The thermoelectric properties of pure and Zn-doped MgO samples were measured by utilizing the Boltztrap package. Structural studies showed that the thin films possess the single phase crystalline cubic structure, which retained its stability after Zn incorporation. The results demonstrated that Zn doping into MgO reduced the optical band gap and enhanced the optical properties. The current research focus indicates that Zn-doped MgO thin films with enhanced optical and thermoelectric properties could be potential choices for optoelectronic and thermoelectric applications. [ABSTRACT FROM AUTHOR]

This research paper explores the structural, electronic, magnetic, elastic, dynamic, and thermoelectric properties of sp-based half-Heusler (HH) RbBaX (X = Si and Ge) compounds using density functional theory (DFT) and the full-potential linearized augmented plane wave (FP-LAPW) method within the WIEN2k software package. We evaluate the exchange correlation potential using two different approaches: The generalized gradient approximation (GGA) and the modified Becke–Johnson approach. We observe that RbBaX (X = Si and Ge) adopts a ferromagnetic configuration based on the analysis of total energy against volume. We establish that these alloys possess a genuine half-metallic character because of the full spin polarization observed at the Fermi level in their electronic spectrum. Both compounds under investigation have a total magnetic moment of 1.00 μ B, in agreement with the Slater–Pauling principle. The Born stability criteria for cubic structures and phonon dispersion patterns confirm the mechanical and dynamic stability of RbBaX (X = Si and Ge) alloys. The thermoelectric properties reveal a p-type semiconductor nature, characterized by significant positive Seebeck values. The thermoelectric figure of merit (ZT) calculated for both alloys at 300 K approaches unity, highlighting their remarkable thermoelectric efficiency. [ABSTRACT FROM AUTHOR]

Double oxide perovskites have recently attracted immense research interest owing to their excellent structural diversities and tunable functional properties, making them promising candidates for renewable energy applications such as photovoltaics, photocatalysis, and thermoelectric devices. In this study, we systematically computed the structural stability, electronic, optical, and thermoelectric properties of a novel perovskite oxide, Ba2KIO6, using first principles calculations within the PBE-GGA and TB-MBJ exchange-correlation functionals. Our results predicted that Ba2KIO6 crystallizes in a stable cubic double perovskite structure. The electronic structure calculations revealed the indirect band gaps of Ba2KIO6 as 0.81 eV with PBE-GGA and 2.1 eV with TB-MBJ. The calculated optical properties, including the dielectric function and optical conductivity, showed strong light absorption in the UV region, highlighting its potential for optoelectronic applications. Furthermore, our calculations of the thermoelectric performance metrics, including the Seebeck coefficient, electrical conductivity, and thermal conductivity, revealed Ba2KIO6 to possess a decent figure-of-merit, highlighting its potential for efficient thermoelectric applications. Overall, our first-principles study provides useful insights into the diverse functional properties of the novel Ba2KIO6 perovskite oxide and suggests its applicability in thermoelectric generators and optoelectronic devices. [ABSTRACT FROM AUTHOR]

CrSi2 thin films with different thicknesses obtained on the Si(111) surface by magnetron sputtering method have been investigated using complex of electron spectroscopy and microscopy methods. The thin films' composition, surface morphology, and cross-section, as well as the resistivity's, Seebeck coefficient's, and power factor's temperature dependences have been studied for the first time. It has been established that, starting from a thickness of ~ 400 Å (deposition time ~ 60 sec), the SiO2/Si(111) surface is completely covered with an amorphous CrSi2 film. After heating the CrSi2/SiO2/Si(111) system at T ≈ 750 K, a homogeneous polycrystalline CrSi2/SiO2/Si(111) film is formed. It is shown that the resistivity ρ, the Seebeck coefficient S, and the power factor P of a CrSi2/SiO2/Si(111) film of different thicknesses (80 and 180 nm) change nonlinearly with increasing temperature. Their values for CrSi2 films of different thicknesses differ slightly from each other. [ABSTRACT FROM AUTHOR]

The present work employs density functional theory to explore the structural, optoelectronic, and thermoelectric attributes of the halide-based double perovskite A2GeSnF6 (A = K, Rb, and Cs) compounds. The stable phonon dispersion spectrum affirms dynamical stability, whereas the enthalpy of formation and tolerance factor evaluated collectively verify structural stability. Considering the Tran Blaha modified Becke Johnson potentials (mBJ), the predicted direct band gaps along the symmetry point are 3.19 eV for K2GeSnF6, 3.16 eV for Rb2GeSnF6 and 3.12 eV Cs2GeSnF6. According to an in-depth examination of the optoelectronic features, A2GeSnF6 (A = K, Rb, and Cs), double perovskites are assuring contenders for optoelectronic devices due to their suitable bandgap. The extremely high figure of merit values (0.94–0.97) obtained from the numerical calculation of power factor and thermal conductivity suggest the intriguing prospects of these compositions for thermoelectric devices. These studies offer a perceptive comprehension of the materials for their potential applications in the future. [ABSTRACT FROM AUTHOR]

Abstract The binary skutterudite CoSb3 is a narrow bandgap semiconductor thermoelectric (TE) material with a relatively flat band structure and excellent electrical performance. However, thermal conductivity is very high because of the covalent bond between Co and Sb, resulting in a very low ZT value. Therefore, researchers have been trying to reduce its thermal conductivity by the different optimization methods. In addition, the synergistic optimization of the electrical and thermal transport parameters is also a key to improve the ZT value of CoSb3 material because the electrical and thermal transport parameters of TE materials are closely related to each other by the band structure and scattering mechanism. This review summarizes the main research progress in recent years to reduce the thermal conductivity of CoSb3-based materials at atomic-molecular scale and nano-mesoscopic scale. We also provide a simple summary of achievements made in recent studies on the non-equilibrium preparation technologies of CoSb3-based materials and synergistic optimization of the electrical and thermal transport parameters. In addition, the research progress of CoSb3-based TE devices in recent years is also briefly discussed.

Thermoelectric material is a kind of functional material that uses the movement of carriers inside a solid to realize the direct mutual conversion of heat and electric energy. It provides a safe, reliable, pollution-free, noise-free, all-solid-state power generation and cooling method and has a wide range of application prospects. Among them, the characteristics of low valence band degeneracy, low effective quality of conduction band, strong phonon non-harmonicity, simple crystal structure and adjustable microstructure have made PbTe-based materials the focus of research in the thermoelectric field. In this review, two latest strategies to improve the thermoelectric properties of PbTe-based materials are discussed, and the challenges for the further development of PbTe-based thermoelectric materials and the prospects for the future are also outlined.

Mechanically robust thermoelectric materials are essential for designing reliable thermoelectric modules. The Bi2Te3‐based alloys show intrinsically poor mechanical properties, thus improving their mechanical performance is of great significance. In this work, the composites of p‐type Bi0.4Sb1.6Te3 and n‐type Bi2Te2.7Se0.3(CuI)0.003 with different K2Ti6O13 whiskers contents are prepared. Due to the grain refinement and the whiskers strengthening mechanism of crack deflection, whiskers pulling out, and whiskers bridging, the mechanical properties of Bi2Te3‐based materials are significantly improved. In addition, the zT value of the Bi2Te3‐based alloys remains almost unchanged compared with the pristine sample. Our study indicates that whiskers strengthening is an effective route to enhance the mechanical properties of thermoelectric materials. [ABSTRACT FROM AUTHOR]

Abstract We develop a facile method to intimately contacted hybrid organic-inorganic nanocomposites as thermoelectric materials. By utilizing branched alkyl naphthalimide molecules as the organic component, monodispersed single walled carbon nanotubes are tethered via strong Van der Waals' forces between the two components (i.e., forming heterojunctions). Comparing with using the linear alkyl naphthalimide molecules as the organic component, this leads to much more intimate contact between the two components, which is identified by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, Raman spectroscopy and Fourier transform infrared spectroscopy. Consequently, the carrier transport is promoted much more at the interface of the branched composites and the thermoelectric properties are enhanced much more compared with those of the linear composites who possess the weaker interactions. The maximum value of the power factor reaches 158.8 μWm−1K−2 while only 85.0 μWm−1K−2 for the linear ones. Because naphthalimide molecules are noncovalently connected to single walled carbon nanotubes, a complex chemical synthesis is avoided, enhancing the use of hybrid nanocomposites in the new energy-related applications, especially the environmentally-friendly applications. We envision that this general, robust and unconventional strategy could be used to create other nanocomposites for use in a variety of applications. Graphical abstract Image 1 Highlights • The hybrid organic-inorganic nanocomposites as thermoelectric materials are prepared. • SWCNTs are tethered with the linear or branched alkyl naphthalimide molecules. • Interactions between the two components are much stronger in the branched composites. • The branched composites display much enhanced thermoelectric properties. [ABSTRACT FROM AUTHOR]

In this paper, we present the effects of annealing in a vacuum on the structural, electrical, thermoelectric, optical and properties of a glass/ITO (40 nm)/Cu (5 nm)/Ni (10 nm)/ITO (40 nm) multilayer prepared on glass substrates at room temperature using the Radio Frequency (RF) sputtering technique. The effect of annealing in a vacuum is investigated. The structures of the ICNI were analyzed using X-Ray Reflectivity (XRR) and X-Ray Diffraction (XRD). Furthermore, the electrical and optical properties were characterized using the four-point probe measurement method and a UV–Vis-NIR spectrometer, respectively. The influence of the annealing temperature in a vacuum on transmittance, structural integrity, electrical behavior, energy band gap, resistivity, Seebeck coefficient, and figure of merit were investigated. [ABSTRACT FROM AUTHOR]

This study computationally investigates the thermoelectric properties of two-dimensional tetragonal Silicene (T-Si) using a tight binding model. The effects of external factors such as bias voltage, magnetic field, and chemical potential on the thermoelectric performance are analyzed through transport coefficients calculated using the Kubo formula and Green's function method. The intrinsic gapless T-Si exhibits tunable electronic structure and thermoelectric properties under these external fields. The results demonstrate that the bias voltage reduces thermoelectric performance due to opening a band gap, while the magnetic field and chemical doping enhance it based on the increasing carrier concentration. The specific heat exhibits a Schottky anomaly peak which its position and intensity modulated by the external fields. Electrical conductivity displays pronounced tuning across temperature ranges under the influence of the fields. The positions, intensities, and magnitudes of power factor, figure of merit, and Seebeck coefficient peaks are sensitively dependent on external parameters. The findings indicate that optimizing the electronic and thermal properties of T-Si using external controlled parameters provides pathways for enhancing the thermoelectric efficiency for thermal energy harvesting applications. [ABSTRACT FROM AUTHOR]