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Recently, photothermoelectric effect of thermoelectric materials has been hotly explored to develop self-powered and large bandwidth photodetectors working at ambient conditions. However, the key parameters for optimized photothermoelectric effect are still elusive. Here, based on the two-temperature model under static condition, we theoretically studied the key parameters to optimize the photothermoelectric performance of thermoelectric materials. Results verify that when the incident electromagnetic wave only generates electronic intra-band excitation, there is an ideal carrier concentration to optimize the photothermoelectric voltage; when the wavelength of a detected electromagnetic wave can resonantly excite quasi-particle (like phonons) except electrons, the photothermoelectric voltage can be enhanced significantly around the resonant wavelength regime; and when the electronic inter-band transition can be excited by an electromagnetic wave, photothermoelectric voltage is significantly increased due to the high optical absorption. As an example, the theoretical dependence of the photothermoelectric voltage of SnSe on wavelength is in line with the experimental result. This work elucidates the crucial parameters of thermoelectric materials to achieve the ideal photothermoelectric performance. [ABSTRACT FROM AUTHOR]

The enhancement of thermoelectric properties in CoS b 3 through atom substitution and hydrostatic pressure application is a promising avenue. Herein, we conducted a comprehensive theoretical investigation into the structural, electronic, and thermoelectric characteristics of CoS b 3 − x A x (A = Ge, Se, Te; x = 0.125, 0.250) using density functional theory coupled with Boltzmann transport theory. By subjecting the system to pressures ranging from 0 to 20 GPa and substituting Sb atoms, we evaluated the enthalpy of formation to predict stability, with CoS b 2.875 T e 0.125 exhibiting superior stability under 20 GPa. The bandgap of doped compounds is direct, ranging from 0.33 to 0.56 eV along the Γ point, and was calculated to elucidate electronic properties. Additionally, employing the Slack model, we computed lattice thermal conductivity based on elastic constants to provide a comprehensive analysis of thermoelectric efficiency. Remarkably, our study not only highlights the effect of hydrostatic pressure on structural and electronic properties but also reveals a beneficial impact on increasing Z T values to 2.77 for CoS b 2.750 G e 0.250 at 800 K and 20 GPa, indicating predominantly p -type behavior. [ABSTRACT FROM AUTHOR]

As a newly synthesized two-dimensional (2D) carbon material, monolayer quasi-hexagonal phase fullerene (qHP C60) has an excellent electronic structure and low thermal conductivity. qHP C60 attracted significant attention from scientists because it has potential applications in thermoelectric materials. Thermoelectric properties of 2D materials significantly depend on the transport of carriers (such as electrons and phonons), and strain engineering is an essential method for modulating the transport of electrons and phonons in 2D materials. However, the strain engineering method for the modulation of the thermoelectric properties of monolayer qHP C60 has not been reported yet. In the present paper, the first-principles combined with the non-equilibrium Green's function method are used to investigate the ballistic transport properties of electrons and phonons in monolayer qHP C60. The effects of temperature, chemical potential, and biaxial tensile strain on the thermoelectric transport parameters (including conductivity, Seebeck coefficient, power factor, and thermal conductivity) as well as the figure of merit (ZT) of monolayer qHP C60 are presented, compared, discussed, and analyzed. We found that monolayer qHP C60 exhibits anisotropic characteristics in electron and phonon transport properties, showcasing outstanding thermoelectric properties. The distinctive quasi-hexagonal phase fullerene network structure offers a novel platform for exploring innovative 2D thermoelectric materials in research. This study provides crucial theoretical insights to guide the designing and implementation of 2D thermoelectric materials based on fullerenes. [ABSTRACT FROM AUTHOR]

This study explores the enhancement of thermoelectric response in a zigzag chain through irradiation with arbitrarily polarized light. The irradiation induces changes in hopping strengths, creating an asymmetric transmission profile around the Fermi energy, which is a crucial factor for achieving a higher figure of merit (FOM). Specific light configurations result in an FOM exceeding unity. We employ the Floquet–Bloch ansatz and minimal coupling scheme to model the irradiation effect, with transport properties evaluated using Green's function technique within the Landauer–Büttiker formalism. The investigation covers electrical conductance, thermopower, and thermal conductance due to electrons and phonons. Our research deepens understanding and opens avenues for tailoring nanostructures to fine-tune thermoelectric properties, advancing highly efficient energy conversion devices exploiting irradiation effects. [ABSTRACT FROM AUTHOR]

Solid-state thermomagnetic modules operating based on the Nernst–Ettingshausen effects are an alternative to conventional solid-state thermoelectric modules. These modules are appropriate for low-temperature applications where the thermoelectric modules are not efficient. Here, we briefly discuss the application, performance, similarities, and differences of thermoelectric and thermomagnetic materials and modules. We review thermomagnetic module design, Nernst coefficient measurement techniques, and theoretical advances, emphasizing the Nernst effect and factors influencing its response in semimetals such as carrier compensation, Fermi surface, mobility, phonon drag, and Berry curvature. The main objective is to summarize the materials design criteria to achieve high thermomagnetic performance to accelerate thermomagnetic materials discovery. [ABSTRACT FROM AUTHOR]

In this study, nanostructures were introduced into bulk Si, and the P content in Si was increased. Arc melting, ball milling, and spark plasma sintering were used to prepare excess P-doped Si samples (Si1−xPx, x = 0.01, 0.03, 0.06, 0.09, and 0.12). In Si0.94P0.06, thermal conductivity decreased to 18 W m−1 K−1 at room temperature, which is about 10% of that of bulk Si. Transmission electron microscopy observation of Si0.94P0.06 revealed a linearly localized alignment, in addition to the nanostructures observed in the previous studies of P-doped Si samples. Linear alignments were composed of Si-P nanoprecipitates and defects linearly localized around dislocations. These sub-microstructures can reduce thermal conductivity; as a result, ZT at 973 K increased to 0.43, which is approximately three times higher than that of single-crystal Si. [ABSTRACT FROM AUTHOR]

This study aimed to determine various thermoelectric properties, including the dimensionless figure of merit (zT0), resistivity (ρTE), thermal conductivity (κTE), and Seebeck coefficient (S), using a combination of 3ω and time-domain impedance spectroscopy (TDIS) methods for a thermoelectric module at absolute temperature (T0). The effective dimensionless figure of merit (zT0,eff), influenced by heat leakage through attached lead wires, was quantitatively and qualitatively assessed based on the TDIS method. The results demonstrated that zT0,eff/zT0 can be expressed as the ratio between the thermal conductance of the attached thermoelectric element and the lead wire. Thus, by considering heat leakage through the lead wire, the TDIS method can estimate not only zT0 and ρTE but also κTE and S after measuring the lead wire's thermal conductivity using the 3ω method. The study utilized a commercial Π-shaped bismuth-telluride-based thermoelectric module and derived representative values for its elements. zT0, ρTE, κTE, and |S| at 300 K were 0.871, 10.15 μΩ m, 1.71 W/mK, and 224 μV/K, respectively, consistent with previous reports on representative bismuth-telluride-based materials. In conclusion, the combination of the 3ω and TDIS methods is useful for determining all thermoelectric properties, considering heat leakage through attached lead wires. [ABSTRACT FROM AUTHOR]

Different from the extensive experimental investigations into the thermoelectric (TE) properties of the bulk IV–VI compounds, less attention has been paid to the TE properties of the monolayer IV–VI compounds. Here, we consider the TE transport properties including the Seebeck coefficient, electronic conductance, thermal conductance, power factor, and figure of merit Z T of the undoped and Bi-doped GeS monolayers. Our results show that for both the undoped and Bi-doped monolayers the anisotropy is widely observed in all their TE properties, and the maximum Z T at a certain temperature along the armchair direction is much greater than that along the zigzag direction. Moreover, Bi doping can lead to an increase of the maximum Z T , and there are more Z T peaks appearing near the zero chemical potential. This indicates that the Bi-doped GeS monolayer can work as a TE material at a lower bias voltage, and especially along the armchair direction it can work at zero bias voltage, which obviously strengthens the reliability of the TE devices. As the temperature increases, the maximum Z T will be uniformally increased along the armchair and zigzag directions for both the undoped and Bi-doped GeS monolayers. In the temperature scope from 300 to 800 K, the maximum Z T along the armchair direction of the Bi-doped GeS monolayer will increase from 3.39 to 4.85, which indicates that this Bi-doped GeS monolayer is a promising TE material in a wide-temperature zone. As an application, we have designed the GeS-based TE couples and found that their efficiencies can be greater than 27 % at large temperature differences. This research should be an important guidance for designing a low-voltage, wide-temperature-scope, and high-stability TE device. [ABSTRACT FROM AUTHOR]

We here report the electronic structure calculation of GaInSe3 and GaInTe3 monolayers with the P3m1 (no. 156) space group. The electronic structure and thermoelectric properties of the monolayers are calculated through the Vienna Ab initio Simulation Package and BoltzTraP2 codes. The dynamic and thermodynamic stabilities were verified by calculating their phonon spectra and simulating ab initio molecular dynamics. The monolayers were found to have a direct bandgap, with both PBE + SOC and HSE06 + SOC potentials. The lattice thermal conductivity of GaInTe3 monolayer calculated using Phono3py code shows ultra-low values due to enhanced phonon–phonon scattering. Combining electrical and thermal transport, the values have been evaluated. Importantly, the p-type GaInTe3 has excellent thermoelectric properties at 700 K, with a z T value of 2, indicating that the p-type GaInTe3 has potential application in the field of thermoelectricity. [ABSTRACT FROM AUTHOR]

MXenes exhibit significant potential in thermoelectric materials owing to their exceptional electrical conductivity; however, their limited number of semiconductors restricts their application. Thus, it is highly desirable to expand the MXene family beyond carbides and nitrides to broaden their applications in thermoelectricity. In this work, we systematically investigate the thermoelectric transport of Ti2OX2 (X = F, Cl) MOene through comprehensively evaluating the electron–phonon coupling (EPC) from first principles. Our findings first emphasize the limitations of the deformation potential theory method and stress the importance of considering EPC. Ti2OF2 (Ti2OCl2) monolayer exhibits exceptional electronic transport, with Seebeck coefficients reaching 1483.87 (1206.22) μV/K and electrical conductivity reaching 9.5 × 105 (7.6 × 105) Ω−1 m−1 at room temperature for its N-type counterpart. Additionally, the presence of degenerate multiple valleys and peaks significantly enhances their electronic transport. For phonon transport, EPC results in a significant reduction in lattice thermal conductivity (kL) [e.g., at 300 K with 1.44 × 1015 (1.68 × 1015) cm−2 of hole, the reduction is 86.3% (73.3%) for Ti2OF2 (Ti2OCl2)]. Additionally, their kL demonstrates a strong correlation with the density of states at corresponding Fermi levels. Moreover, the kL and total thermal conductivity of P-type Ti2OF2 show T-independence, making it suitable for applications in aviation and thermal insulation materials. Finally, N-type Ti2OF2 and Ti2OCl2 demonstrate superior zT values of 0.63 and 0.9 at 900 K, respectively. This study provides in-depth insights into the superior thermoelectric properties of Ti2OX2 (X = F, Cl) MOene with considering EPC, providing a novel platform for the next-generation thermoelectric field. [ABSTRACT FROM AUTHOR]

The authors investigate the influence of local polarization on the thermoelectric properties of monolayer MoS2 using a tight-binding approach. It is found that strain-induced polarization in armchair monolayer MoS2 can be easily embedded to strongly enhance the thermoelectric efficiency ZT for quantum wells. The structure we proposed can achieve a figure of merit ZT of 0.8 at room temperature in an armchair MoS2 nanoribbon, and ZT achieves 1 at 500 K. The results facilitate insight and understanding of strain modulated thermoelectric properties of monolayer MoS2 nanodevices, provide theoretical guidance for experiments, and indicate their great potential in thermoelectric devices. [ABSTRACT FROM AUTHOR]

The authors investigate the influence of local polarization on the thermoelectric properties of monolayer MoS2 using a tight-binding approach. It is found that strain-induced polarization in armchair monolayer MoS2 can be easily embedded to strongly enhance the thermoelectric efficiency ZT for quantum wells. The structure we proposed can achieve a figure of merit ZT of 0.8 at room temperature in an armchair MoS2 nanoribbon, and ZT achieves 1 at 500 K. The results facilitate insight and understanding of strain modulated thermoelectric properties of monolayer MoS2 nanodevices, provide theoretical guidance for experiments, and indicate their great potential in thermoelectric devices. [ABSTRACT FROM AUTHOR]

In this study, the basic properties of Ba2AgSi3 were investigated in detail from both experimental and computational viewpoints. Polycrystalline Ba2AgSi3 formed by an arc-melting apparatus under an argon atmosphere was ground into powders, and then powder samples were sintered using the spark plasma sintering method. Both n-type and p-type samples were obtained. This may be due to a slight deviation from the stoichiometric composition. The energy bandgap of Ba2AgSi3 was measured to be around 0.17 eV from the temperature dependence of electrical conductivity and was in agreement with that by first-principles calculations. Sintered samples exhibited a high Seebeck coefficient of −273 μV K−1 and a high power factor of 0.38 mW m−1 K−2 at 307 K for n-type samples. They were 217 μV K−1 and 0.23 mW m−1 K−2, respectively, at 320 K for p-type samples. The electronic structures of impurity-doped Ba2AgSi3 were also discussed using first-principles calculations to investigate the insertion site of impurity atoms. The calculations suggest that the substitution of B (P) at any Si site shifts the Fermi level and transforms it into p-type (n-type) semiconductors. On the other hand, substitution of Ba or Ag sites with B or P is unlikely to occur in terms of formation energy. [ABSTRACT FROM AUTHOR]

The evaluation of thermoelectric materials relies significantly on the thermoelectric figure of merit, ZT, which serves as a crucial parameter in assessing their properties. The accurate prediction of ZT values can be accomplished by utilizing machine learning models to learn material characteristics. However, factors such as the size of the dataset, model hyperparameters, and data quality can all impact the accuracy of machine learning. In contrast to previous research where high-dimensional features were simply discarded to transform them into low-dimensional ones, deep learning models such as autoencoder can extract more effective information. Therefore, in this article, the combination of autoencoders and the Light Gradient Boosting Machine (LightGBM) is employed to learn the chemical characteristics and ZT values of various materials. The reliability of the model was confirmed by achieving an R2 score of 0.94 during tenfold cross-validation. 130 000 materials were predicted and screened, the temperature dependence of the screened materials was studied in depth, and 13 materials with high ZT values were identified. Four of the 13 most promising candidates identified are existing thermoelectric materials, while nine are ideal candidates for future experimental studies and validation. This work utilizes autoencoders for extensive prediction and screening of promising materials, providing an effective approach for handling high-dimensional material data. [ABSTRACT FROM AUTHOR]

This paper investigates a systematic theoretical study of the lattice dynamical, electronic, and thermoelectric transport properties of PbTe, which is subjected to hydrostatic pressure and uniaxial stress along the [100], [110], and [111] directions, by using first-principles calculations. Our study demonstrates that stress is an effective tool for regulating thermoelectric properties in materials, and different types of stress affect these properties through distinct mechanisms. Specifically, under hydrostatic pressure and uniaxial stress along the [100] direction, PbTe exhibits similar electronic behavior but different lattice dynamical properties. Bandgap closure and reopening are observed under hydrostatic pressure and uniaxial stress along the [100] direction, whereas only the gap opposite trends are seen for uniaxial stress along the [110] and [111] directions. Under uniaxial stress along the [100] direction, phonon lifetimes decrease, leading to low thermal conductivity. In contrast, under hydrostatic pressure and uniaxial stress in the [110] and [111] directions, phonon lifetimes are enhanced due to a weakening of the anharmonic effect. Our findings provide a comprehensive understanding of the implication of different stress types on the thermoelectric properties of PbTe. [ABSTRACT FROM AUTHOR]

Based on first-principles calculations, the current study deeply explores the thermoelectric properties of the Zintl compound SrPdTe. We found that the anharmonic vibration of Pd atoms plays an important role in the quartic anharmonic effect and the temperature dependence of the thermal conductivity. In the crystalline structure, Sr atoms form octahedra with eight surrounding Te atoms, while Pd atoms are located in the gaps between the octahedra. This structure makes the strong atomic mean square displacement of Pd atoms the main factor leading to the ultralow thermal conductivity. The study also reveals the effects of phonon frequency renormalization and four-phonon scattering on heat transfer performance. Even considering the spin–orbit coupling effect, multiple secondary valence band tops maintain the power factor of the material at high temperatures, providing a potential opportunity for achieving excellent thermoelectric performance. [ABSTRACT FROM AUTHOR]

A series of Sr0.7Ba0.3Nb2O6−δ/x wt. % Ti (x = 1, 3, 5, and 10) composite ceramic thermoelectric materials were prepared, and the mechanism for improving their thermoelectric properties was explored. The experimental results demonstrate that nano-additive titanium powder undergoes oxidation to form TiO2 during sintering. However, under annealing in a reducing atmosphere, oxidation reactions further deplete the lattice oxygen, leading to an increased generation of oxygen vacancies and enhanced carrier concentration, ultimately leading to successful resistivity reduction. The samples consistently exhibit low thermal conductivity values below 2.0 W m−1 K−1 due to crystal defects, complex structure, and phonon scattering at the grain boundaries. The sample doped with 5 wt. %. Ti exhibits the lowest resistivity and highest PF value (409.3 μW/m K2 at 1073 K). Consequently, the figure of merit of Sr0.7Ba0.3Nb2O6−δ with 5 wt. % Ti attains its maximum value of 0.30 at 1073 K, representing a 50% increase compared to that of the undoped sample Sr0.7Ba0.3Nb2O6−δ (0.20 at 1073 K). [ABSTRACT FROM AUTHOR]

Tetrahedrite, Cu12Sb4S13, an eco-friendly thermoelectric material with earth-abundant and low-cost constituents, has garnered global interest. This study investigated the thermoelectric characteristics of Ag-added tetrahedrites, which were prepared through solid-state synthesis and subsequently hot-pressed. The minimal temperature dependence of the transport coefficient indicated the presence of strong electron–phonon coupling in the samples. It was observed that Ag addition in tetrahedrite could successfully scatter acoustic phonons, reducing the lattice thermal conductivity while minimally affecting the power factor. The enhanced anharmonicity induced by Ag addition is the primary cause of reduced lattice thermal conductivity. Raman spectroscopy data showed that Ag addition could weaken the Sb–S bond, further supporting the previous argument. Consequently, the lattice thermal conductivity was lowered to ∼0.27 W m−1 K−1 and obtained for the composition Ag0.025 added Cu11.975Sb4S13. A relatively high power factor of ∼1.3 mW m−1 K−2 was obtained for the same composition. Owing to the lowest total thermal conductivity ∼1.09 W m−1 K−1, the sample with composition Ag0.025 added Cu11.975Sb4S13 showed the highest thermoelectric figure of merit of 0.87 at 738 K. [ABSTRACT FROM AUTHOR]

Due to their potential applications in energy production based on waste heat, direct solar radiation or other energy sources, semiconductor materials have for years attracted the attention of theoretical and experimental researchers. The focus has been on improving the performance of thermoelectric devices through several strategies and special interest has been placed on materials with spatially inhomogeneous transport properties. Inhomogeneity can be achieved in various ways, all of them leading, to a greater or lesser extent, to an improvement of the thermoelectric performance. In this paper, general linear heat and electric charge transport processes in inhomogeneous materials are addressed. The guiding idea followed here is that there exists a relationship between inhomogeneity (structuring), minimum entropy production and performance which may be fruitfully exploited for designing more efficient thermoelectric semiconductor devices. We first show that the stationary states of such materials are minimum global entropy production states. This constitutes an extension of the validity of Prigogine's minimum entropy principle. The heat and charge transport equations obtained within the framework of classical irreversible thermodynamics are solved to find the stationary profiles of temperature and self-consistent electric potential in a one-dimensional model of a silicon–germanium alloy subjected to an external temperature difference. This allows us to assess the effect of the spatial inhomogeneity on the thermoelectric performance. We find that, regardless of the value of the applied temperature difference, the system may efficiently operate in a regime of minimum entropy production and high efficiency. [ABSTRACT FROM AUTHOR]

The choice of exchange functional is a critical factor in determining the energy bandgap of semiconductors. Ab initio calculations using different exchange functionals, including the conventional generalized-gradient approximation (GGA) functionals, meta-GGA functionals, and hybrid functionals, show significant differences in the calculated energy bandgap for semiconducting half-Heusler compounds. These compounds, which have 18 valence electrons per unit cell, are of great interest due to their thermoelectric properties, making them suitable for energy conversion applications. In addition, accounting for electronic correlations using the G W method also affects the calculated energy bandgaps compared to standard GGA calculations. The variations in calculated energy bandgaps are specific to each material when using different functionals. Hence, a detailed investigation of the electronic properties of each compound is necessary to determine the most appropriate functional for an accurate description of the electronic properties. Our results indicate that no general rules can be established and a comparison with experimental results is required to determine the most appropriate functional. [ABSTRACT FROM AUTHOR]

Ferroelectric (FE) electrocaloric materials research has been blossoming worldwide for solid-state refrigeration and potential cooling systems replacing thermoelectric Peltier coolers in microelectronics. In this work, we report the outcomes from a systematic study of combined phase transition (thermodynamics) based on the phenomenological Landau theory and distributed electric field (electrostatics of thin film interfaces) in FE bilayer films. Specifically, the compositional variation of ferroelectric bilayers results in broken spatial inversion symmetry leading to asymmetric thermodynamic potentials due to a combination of normal (first- and second-order phase transition) and relaxor (dispersive dielectric constant) ferroelectric behaviors devised for efficient electrocaloric cooling effects. Extensive theoretical analyses conducted for bilayers consisting of insulating materials highlight modified phase transition temperature behavior and self-poling by effective electric field amplification arising due to bilayers' electrostatic coupling yielding significant changes in isothermal entropy (ΔS) and adiabatic temperature (ΔT). The theoretical calculation insights supported with experimental results signify, through case studies for a combination of materials experimental parameters, that amplification of the local electric field and materials engineering maximize the number of coexisting phases at or away from the morphotropic phase boundary of constituent layers in bilayer thin film architectures, which can be applicable toward other classes of materials and multilayer systems. These are effective ways for efficient cooling, in general, and for microelectronics thermal management either directly or by developing a thermal switch with phase change materials integrated with thermoelectric coolers for residual heat dissipation, both at the system and on-chip levels. [ABSTRACT FROM AUTHOR]

The direct conversion of thermal energy into electrical current via thermoelectric (TE) effects relies on the successful integration of efficient TE materials into thermoelectric generators (TEGs) with optimized characteristics to ensure either optimum output power density or conversion efficiency. Successfully employed for powering deep-space probes and extraterrestrial rovers since the 1960s, the development of this technology for waste-heat-harvesting applications faces several key issues related to the high temperatures and oxidizing conditions these devices are subjected to. This Perspective provides a brief overview of some prospective thermoelectric materials/technologies for use in radioisotope thermoelectric generators utilized in space missions and highlights the progress made in the field over the last years in the fabrication of TEGs. In particular, we emphasize recent developments that enable to achieve increased power densities, thereby opening up novel research directions for mid-range-temperature applications. In addition to showing how using lower quantities of TE materials may be achieved without sacrificing device performance, we provide an outlook of the challenges and open questions that remain to be addressed to make this technology economically and technologically viable in everyday-life environments. [ABSTRACT FROM AUTHOR]

An innovative electromagnetic energy harvester was developed using a compact four-ring single-resistor unit cell. To achieve efficient conversion of electromagnetic waves into electricity, we integrated the high-performance Bi2Te3 thermoelectric material onto the load resistor. Remarkably, this unit cell exhibits exceptional energy harvesting capabilities at a frequency of 5.8 GHz while maintaining polarization insensitivity. Through comprehensive analysis, we evaluated the energy harvesting efficiencies, power loss distribution, and current density distribution. Additionally, we investigated the impact of incident power on the unit cell's temperature and energy conversion efficiencies. To enhance energy concentration on the load, we ingeniously designed an "L-shaped" metal through-hole structure within the four-ring single-resistor unit cell. Our results demonstrate that the four-ring single-resistor unit cell achieves an impressive harvesting efficiency of 94.5% at 5.8 GHz, with a thermal conversion efficiency of 43.3 °C/W, an electrical conversion efficiency of 0.23 mV/°C, and an electrical response rate of 9.4 mV/W. Notably, when subjected to a power input of 7 W, the unit cell produces an output voltage of 65.9 mV, and its theoretical maximum output power reaches 180 mW. [ABSTRACT FROM AUTHOR]

Tunable lattice thermal conductivity is a critical issue promoting thermoelectric performance of potential thermoelectric materials. Herein, the effects of biaxial strain and an external electric field on the lattice thermal conductivity of monolayer AlP3 have been investigated systematically by solving the phonon Boltzmann transport equation based on first-principles calculations. Our results imply that the lattice thermal conductivity of monolayer AlP3 can be effectively modulated in a wide range depending on the applied in-plane biaxial tensile strains or out-of-plane external electric fields. Once the biaxial tensile strain is applied to the monolayer, the lattice thermal conductivity exhibits an up-and-down behavior with an increase in the tensile strain. The maximum thermal conductivity is obtained at a tensile strain of 6%, and a surprising peak value of 13.8 times higher than that of the pristine monolayer can be achieved, whereas the lattice thermal conductivity of monolayer AlP3 is able to be further suppressed by applying an external electric field, and a minimum value of about 47.5% of the pristine one can be observed by utilizing an electric field of 0.06 eV/Å. Thus, this work highlights that biaxial strain combined with an external electric field can provide effective ways to realize robust thermal management for 2D triphosphides. [ABSTRACT FROM AUTHOR]

Thermoelectric materials can directly convert between thermal energy and electrical energy, and their efficiency is determined by the average dimensionless figure of merit ZT. The crystal SnSe has been discovered with unique transport features and ultra-high ZT values. Considering the high production cost, long processing time, and poor mechanical properties of crystal SnSe, it is important to achieve mass production and commercial applications in polycrystal SnSe with good processability and low cost. This perspective summarizes the strategies to improve the thermoelectric properties of polycrystal SnSe, including composition control to tune the carrier concentration and modify the band structure, and process control to texture the grains and remove oxides, which all mainly focused on enhancing the peak ZT values of polycrystal SnSe. Recently, a novel structure control strategy was implemented to modulate the crystal structure of SnSe. By alloying proper ternary compounds, the cubic-structure polycrystal SnSe was obtained with completely different thermoelectric transports and high-ranged overall ZT values. This structure control strategy offers an effective way to enhance the wide-range thermoelectric performance of polycrystal SnSe and provides a new research idea for the development of highly efficient thermoelectric materials, especially for those with low-dimensional structures. [ABSTRACT FROM AUTHOR]

Thermal conductivity and power factor are key factors in evaluating heat transfer performance and designing thermoelectric conversion devices. To search for materials with ultralow thermal conductivity and a high power factor, we proposed a set of universal statistical interaction descriptors (SIDs) and developed accurate machine learning models for the prediction of thermoelectric properties. For lattice thermal conductivity prediction, the SID-based model achieved the state-of-the-art results with an average absolute error of 1.76 W m−1 K−1. The well-performing models predicted that hypervalent triiodides XI3 (X = Rb, Cs) have ultralow thermal conductivities and high power factors. Combining first-principles calculations, the self-consistent phonon theory, and the Boltzmann transport equation, we obtained the anharmonic lattice thermal conductivities of 0.10 and 0.13 W m−1 K−1 for CsI3 and RbI3 in the c-axis direction at 300 K, respectively. Further studies show that the ultralow thermal conductivity of XI3 arises from the competition of vibrations between alkali metal atoms and halogen atoms. In addition, at 700 K, the thermoelectric figure of merit ZT values of CsI3 and RbI3 are 4.10 and 1.52, respectively, at the optimal hole doping level, which indicates hypervalent triiodides are potential high performance thermoelectric materials. [ABSTRACT FROM AUTHOR]

Organic/inorganic thermoelectric hybrids demonstrate great potential for wearable applications. However, their scalability is hindered by an inferior power factor (S 2 σ). Nowadays, achieving deep optimization of S 2 σ necessitates a strategy to decouple the Seebeck coefficient (S) and electrical conductivity (σ). In this work, we propose a strategy to break the coupling between S and σ by constructing a Schottky interface that exhibits an energy-filtering effect. We validate the feasibility of this approach using a PANI/TiN–TiO2/carbon paper. The results demonstrate a 1.16-fold increase in σ and a 1.08-fold increase in S in PANI/TiN–TiO2/carbon paper achieved through the construction of a Schottky-type TiN/TiO2 interface. The separation of hole/electron at the TiN/TiO2 interface serves as the scattering center for ionized impurity scattering and facilitates the transport pathway for charge carriers. These factors are crucial in determining the simultaneous optimization of S and σ , respectively. Additionally, the energy-filtering effect of the TiN/TiO2 interface plays a positive role in the ionized impurity scattering mechanism by selectively filtering out low-energy carriers. This further strengthens decoupling of the thermoelectric properties. The 14.9% PANI/11.2% TiN–14.5% TiO2/59.44% carbon paper displays the highest S 2 σ and achieves a high ZT value of 223.6 μVm−1 K−2 and 0.31 at 300 K, highlighting the advantages of PANI-based thermoelectric hybrids. This work provides valuable guidance for the design of thermoelectric hybrids incorporating multi-interface morphology. [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]

In this study, we have investigated the effect of strontium (Sr) doping on the thermoelectric properties of thin films made of tin telluride (SnTe). The preparation of Sn 1-x Sr x Te (x = 0, 0.1, 0.2, 0.3, 0.4) films using a straightforward thermal evaporation method and subjected them to post-annealing at 773 K. The surface morphology and crystal structure of the films have been examined by using SEM and XRD, respectively. Our findings indicate that the Seebeck coefficient value increased from 39 to 68 μV/K as the Sr doping concentration increased. This enhancement has been attributed to the energy filtering effect resulting from charge carrier dislocation. However, the electrical conductivity value decreased due to an increase in defect density. The maximum enhancement of the power factor has been observed for x = 0.3, where the value reached 38.9 μWcm−1K−2, which is greater than the pristine sample. Our results conclude that Sr 0.3 doping in Sn 0.7 Te is a valuable addition for thermoelectric applications at room temperature. Additionally, the use of the simple thermal evaporation method for film preparation highlights its potential for large-scale applications. [ABSTRACT FROM AUTHOR]

Higher manganese silicides have evolved as an efficient thermoelectric material because of their exceptional thermoelectric performance at intermediate temperatures. In this work, we report the ultralow-thermal conductivity with improved thermoelectric properties of Mn 1-x Cr x Si 1.8 (x = 0, 0.025, 0.05 and 0.1) prepared by induction melting followed by ball milling and uni-axial induction hot-pressing. Bragg diffraction patterns confirmed that the as-synthesized compound belongs to the Mn 15 Si 26 phase along with the solid solubility of Cr in the HMS lattice. In addition, the backscattered electron micrographs revealed the precipitation of excess Si in the HMS matrix, originating from Si-rich stoichiometry. Furthermore, an elevation in electrical conductivity with increasing Cr content has been observed because of its acceptor dopant behaviour at the Mn site. On the contrary, the Seebeck coefficient decreased upon an increase in Cr content, and bulk MnSi 1.8 has shown the highest Seebeck coefficient of 220 μV/K at 773 K. Impressively, nanostructuring along with the generated point defects as a result of Cr dopant facilitates an intensified phonon scattering at the nanostructured grain boundaries that results in a very low κ total of 0.99 W/mK at 773 K for ball-milled Mn 0.9 Cr 0.1 Si 1.8 , leading to an elevated zT of 0.46 at 773 K. [ABSTRACT FROM AUTHOR]

This work addresses the problem of obtaining of Ca 3 Co 4 O 9+δ -based ceramics with enhanced thermoelectric performance. Phase-inhomogeneous layered calcium cobaltite ceramics with cationic nonstoichiometry were prepared by solid-state reactions method and a field assisted sintering technology (FAST). Comprehensive experimental characterizations were conducted on the prepared bulk samples, focusing on their phase composition, as well as thermal (including thermal expansion, thermal diffusivity, and thermal conductivity), electrical (encompassing electrical conductivity and the Seebeck coefficient), and functional properties (such as power factor and figure-of-merit). The FAST technique allowed to obtain ceramics with low porosity and high electrical conductivity, which increased as the Ca:Co ratio within the samples decreased, while sample phase inhomogeneity considerably increased the Seebeck coefficient. The best thermoelectric performance was demonstrated for cationic nonstoichiometric Ca 3 Co 4.4 O 9+δ , which power factor and figure-of-merit values at 825 °C reached 427 μW⋅m−1⋅K−2 and 0.146, respectively. • Ca 3 Co 4 O 9+δ -based ceramics prepared by field assisted sintering technology possessed low porosity and high conductivity. • Electrical conductivity of bulk samples increased at decreasing Ca:Co ratio. • Phase inhomogeneity of prepared ceramics increased the Seebeck coefficient. • Ca 3 Co 4.4 O 9+δ ceramics showed the best thermoelectric performance. [ABSTRACT FROM AUTHOR]

This study was focused on unraveling the close dependence of the structural, morphological, and thermoelectric properties of sputtered ZnO films on base pressure. The ZnO film deposited at an optimized base pressure of 5 × 10−6 torr exhibited the highest thermoelectric power factor of 374.6 μW/mK2, corresponding to an electrical conductivity of 265 S/cm and a Seebeck coefficient of −124 μV/K at 583 K. The obtained results revealed that the positive effect of base pressure on enhancing thermoelectric properties of ZnO films is attributed to point-defect modification, including zinc vacancies, singly-, and doubly-charged oxygen vacancies. Based on these results, we propose that defect engineering is a facile and effective approach for improving the thermoelectric behavior of ZnO films, even without doping by controlling the sputtering conditions. [Display omitted] [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]

The Mercury Sulphohalides have attracted significant attention in the fields of solar cells and thermoelectric applications. This study delves into the fundamental characteristics, including structural, elasticity, electronic behavior, phonon stability, optical properties, and transport features of AgHgSZ (Z = Br, I) through computational simulations based on Density Functional Theory (DFT) using WIEN2k software. Meticulous calculations of the phonon band structure ensure dynamic stability. The semiconductor nature with indirect band gaps (1.833 eV and 1.832 eV) for Mercury Sulphohalides (Br, I), as revealed by their band structures, suggests diverse photovoltaic and transport applications. Mechanical assessments show stable ductility for AgHgSBr and brittleness for AgHgSI, along with anisotropy and resistance to scratching. Optical properties exhibit anisotropy and significant UV absorption. Analysis of effective masses, exciton binding energy, and exciton Bohr radius suggests low exciton binding energy and classification under Mott-Wannier excitons. Positive thermopower results indicate holes as the predominant charge carriers in AgHgSBr and AgHgSI materials. Moreover, essential thermoelectric factors are examined, revealing the compounds' potential for thermoelectric applications. Notably, the figure of merit (ZT) at 300 K for AgHgSBr and AgHgSI are calculated to be 0.41 and 0.13, respectively. While these values are low at 300 K, they indicate promising potential for thermoelectric applications at higher temperatures. In summary, this investigation provides valuable understanding into the photovoltaic and thermoelectric properties of AgHgSZ (Z = Br, I) materials, potentially paving the way for further exploration in this domain. [ABSTRACT FROM AUTHOR]

Hydrogels are renowned for their complex structures and unique physicochemical properties, establishing them as key materials in bioenergy harvesting applications. They are used in various applications, including triboelectric nanogenerators, piezoelectric, hydraulic, thermoelectric, and biofuel cells. Among these, hydrogels as key materials for thermoelectric applications represent a technology capable of continuously converting biological energy (thermal energy) into electrical energy. This technology shows great potential and commercial value in body monitoring, energy storage, and human‐machine interaction applications. Given its rapid development, a timely review focusing on the research progress of hydrogels and their composites in thermoelectric technology is presented. This review discusses various types of hydrogels used for thermoelectric power generation and refrigeration, their unique properties, strategies for enhancing their thermoelectric performance, and their applications in the field. Finally, the remaining challenges and feasible strategies are identified for improving the efficiency, stability, application range, and system‐level integration of next‐generation hydrogels for thermoelectric 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]

The freeze‐casting method shows great potential for environmentally friendly and industrial scale‐up application in thermoelectric materials due to low cost, low toxicity, and pore control. The porous Ca3Co4O9 ceramics with anisotropic thermoelectric performance were fabricated by the freeze‐casting method. High porosities, hierarchical pores, and three‐dimensional (3D) networks significantly contributed to the suppressed thermal conductivity. An ultralow total thermal conductivity of 0.21 W/(m·K) was obtained. The optimized freeze‐casting conditions gave rise to a Seebeck coefficient of 232.3 µV/K. In addition, the ZT value of 0.39 was obtained at 800°C due to the manipulation of hierarchically connected pores and small portions of isolated hexagonal pores. This work provides a new route to form the 3D pores network in oxide thermoelectric ceramics, leading to a decrease in thermal conductivity and optimized thermoelectric performance parallel to the freeze‐casting direction. [ABSTRACT FROM AUTHOR]

Oxides are attractive and promising compounds for application as thermoelectric materials owing to thermal and chemical stability, cost-effectiveness, and environmental safety. In this work, CaMnO 3 perovskite hollow spheres were synthesized by spray solution combustion synthesis. The effect of the fuel glycine on the phase composition, morphology, and microstructure of CaMnO 3 was studied, and the influence of synthesis parameters on the characteristics of the sintered materials was investigated. The porous CaMnO 3 (porosity 10–20%) forms by pressureless sintering at 1473 K, which is accompanied by the precipitation of marokite CaMn 2 O 4. It is possible to alter the porosity level as well as marokite and pore size in the CaMnO 3 /CaMn 2 O 4 composite by tailoring the fuel amount, which, in turn, affects the thermoelectric properties. The zT value of 0.13 at 1073 K, to the best of our knowledge, is the highest zT reported for the undoped CaMnO 3 material. • Hollow Spheres of CaMnO 3 Produced via Spray Solution Combustion Synthesis (SSCS). • Increasing fuel during SSCS reduced wall thickness of hollow spheres from 140 to 40 nm. • Excess fuel negatively affected CaMnO 3 uniformity after sintering. • Pressureless sintering yields bulk homogeneous CaMnO 3 + 10 vol% CaMn 2 O 4 + 22% pores. • Porosity and marokite of CaMnO 3 perovskite increase zT value at 1073 K to 0.13. [ABSTRACT FROM AUTHOR]

Ternary half-Heusler (HH) alloys are under intense investigations recently towards achieving high thermoelectric (TE) figure-of-merit (ZT). Of particular interest is the ZrNiPb-based HH alloy, where an optimal value of ZT ~ 0.7 at 773 K has been achieved by co-doping Sn and Bi at Pb site. In this work, we identify an excellent ZT of 1.3 in ZrNi1+xPb0.38Sn0.6Bi0.02 (x = 0.03, at 773 K) composite alloy. This is achieved by synergistic modulation of electronic as well as thermal properties via introduction of minor phase of full-Heusler (FH) in the HH matrix through compositional tuning approach. These Ni-rich ZrNi1+xPb0.38Sn0.6Bi0.02 (0 ≤ x ≤ 0.07) alloys were synthesized via energy efficient and time-curbed techniques that involved Arc melting followed by consolidation via spark plasma sintering. These alloys were characterized by XRD and SEM, which show formation of nanocomposites comprising of HH matrix phase and FH secondary minor phases. Enhancement in ZT is mainly attributed to a synchronized increase in power factor (~42%) and ~25% decrease in its thermal conductivity. Here, TE compatibility factor (S) was also calculated for all samples. The value of |S| ~ 2.7 V−1 (at 773 K) is observed for x = 0.03, which is ~17% higher than bare HH composition (x = 0.0). The theoretically calculated TE device efficiency of best-performing sample ZrNi1.03Pb0.38Sn0.6Bi0.02 is estimated to be η ~ 13.6%. Our results imply that deliberately controlled fine tuning in compositions of HH compounds through compositional tuning approach would lead to novel off-stoichiometric HH phases with enhanced ZT value for efficient TE device fabrication. [ABSTRACT FROM AUTHOR]

Rhombohedral GeSe is a promising p‐type thermoelectric material, noted for its low toxicity, environmental friendliness, and greater affordability compared with tellurides. However, its thermoelectric performance still requires further enhancement for practical applications. In this work, a highly competitive peak figure of merit (ZT) of 1.24 at 623 K for p‐type polycrystalline Ge0.895Cu0.005Se0.9(AgBiTe2)0.1, along with a high average ZT of 0.74 between 323 K and 623 K is reported. Comprehensive micro/nanostructural characterization reveals that alloying with AgBiTe2 and doping with Cu successfully induce dense point defects, secondary Ag2Te phases, and various nanoprecipitates in the GeSe matrix. These abundant crystalline and lattice defects result in strong phonon scattering, leading to an ultra‐low lattice thermal conductivity of 0.35 W m−1 K−1 at 623 K. Moreover, Cu doping enhances carrier mobility, promoting decoupling between carriers and phonons. This allows for low thermal conductivity and high power factor coexistence to achieve a high ZT. Additionally, with a temperature difference of 325 K, the theoretical energy conversion efficiency reaches up to 8.5%, indicating great potential for medium‐temperature device applications. This work suggests that Cu doping is an effective strategy for achieving high thermoelectric performance in rhombohedral GeSe‐based materials. [ABSTRACT FROM AUTHOR]

Sodium cobaltite (NaxCoO2) is one of the most renowned and thermoelectrically promising p‐type cobalt oxide materials, showing exceptional performance in this domain. Nonetheless, its thermal instability in air renders it unsuitable for high‐temperature applications such as energy harvesting from industrial waste heat. To utilize the beneficial properties of NaxCoO2, microscale NaxCoO2 template particles of significantly larger size were effectively embedded within a thermally stable Ca3Co4−yO9+δ–NaxCoO2–Bi2Ca2Co2O9 triple‐phase matrix. This approach additionally aimed to enhance the texture and boost the thermoelectric performance of the ceramic composite. Highly textured p‐type ceramic composites were fabricated via uniaxial cold‐pressing and pressureless sintering in air. The unique hexagonal NaxCoO2 template particles, produced through molten‐flux synthesis, allowed precise control over their shape and dimensions, while the matrix was synthesized via a sol–gel synthesis. The integrated NaxCoO2 particles of the textured composite exhibited increased thermal stability, showing no sign of decomposition at 1173 K in air, whereas the sole template particles decomposed at 1073 K during sintering. A 20 wt% template particle content in the textured composites resulted in a remarkably high and nearly temperature‐independent power factor of 8.8 µW cm−1 K2, corresponding to an improvement of 13% compared to that of the pure matrix material. [ABSTRACT FROM AUTHOR]

The efficient production and sustainable operation of water electrolysis hydrogen production equipment within renewable energy systems, characterized by intermittency and volatility, necessitates dynamic simulation for the development of optimized control systems. This paper proposes the application and modification of a data-driven deep-learning model to simultaneously simulate the thermal and electrochemical responses of an alkaline water electrolyzer (AWE), yielding exceptional performance and versatility. By utilizing 4840 h of comprehensive experimental data, the causal relationships among electrolyzer operating parameters are resolved, classifying them into set values and response values for the proposed dynamic model. The model architecture is based on an attention mechanism and designed with hybrid input. Notable enhancements include embedding flow-leveraged polarization function, creating set-value cross-attention, and adopting probability-sparse attention, all of which are validated through both the validation and simulation results. Extensive exploration of various structural and training parameters leads to the selection of the best-performing model. When applied to simulation across all experimental data, the median mean percentage absolute error of the optimal model in cell voltage is a mere 1.3%, while the error in temperature is only 3.5%. Moreover, under typical operating conditions, the simulation error for both voltage and temperature remain below 2%, highlighting the outstanding dynamic modeling and simulation capabilities. These results demonstrate the potential of the proposed model for future hydrogen energy applications in dynamic control and operational optimization within renewable energy system for higher performance and better conversion efficiency. • Deep-learning model for dynamic thermoelectric simulation of water electrolyzers. • Flow-leveraged polarization function and set-value cross-attention mechanism. • Excellent accuracy, thermoelectric error of 3.5% and 1.3%, respectively. • Insights for optimizing control strategies of electrolyzer for higher efficiency. [ABSTRACT FROM AUTHOR]

The coupling relationship between electrical and thermal transports makes it rather challenging to enhance thermoelectric performance. Here, electrical and thermal transports are successfully decoupled to realize high performance in n‐type PbSe by utilizing a stepwise strategy. First, the PbSe lattice is plained with extra Pb to compensate for the intrinsic Pb vacancies, which can weaken defect scattering and improve carrier mobility to ≈1230 cm2 V−1 s−1. The room‐temperature power factor triples and reaches ≈32 µW cm−1 K−2, and ZT is significantly enhanced to ≈0.6 in Pb1.006Se. Subsequently, liquid‐like interstitial Cu ions are introduced to inhibit heat conduction without damaging electrical transport. While maintaining a high power factor of ≈25 µW cm−1 K−2, Cu ions strongly suppress phonon transport at high temperature, leading to an ultralow lattice thermal conductivity of ≈0.28 W m−1 K−1 in Pb1.006Cu0.006Se, only 30% of the Cu‐free PbSe. Eventually, a remarkable peak ZT of ≈1.8 at 773 K is achieved along with a high average ZT of ≈1.1 from 300 to 823 K in Pb1.006Cu0.006Se. An outstanding experimental conversion efficiency of ≈7.1% is obtained in the single‐leg device, demonstrating great potential for PbSe as low‐ to mid‐temperature thermoelectrics. [ABSTRACT FROM AUTHOR]

The Zn─Sb binary system contains two high‐performing thermoelectric materials, namely the ordered ZnSb and the disordered Zn13Sb10. Both systems exhibit low thermal conductivity, which is speculated to originate from multicentre bonding within Zn2Sb2‐rhombi. Here, the electron density of ZnSb is reported based on multipole modelling of accurate X‐ray diffraction data measured at 20 K. Topological analysis reveals that the bond paths in the rhombus are endocyclically strained and that electron density is concentrated within the rhombus rather than along its geometric bonds consistent with a multicentre bond description. However, the electron density is not equally shared between the geometric bonds of the rhombus. Electron density analysis and modelling of low‐temperature anharmonicity reveal that one Zn–Sb interaction is weaker than the other. Taken together with the orientation of bonds external to the rhombus structure, an alternative description emerges wherein the multicentre bond is more partially localised along one set of the opposite legs of the rhombus. In this description, the stronger bond can be considered a traditional 2‐centre‐2‐electron bond, while the weaker interaction is coordinative to the covalent bond. The anharmonicity and low thermal conductivity may consequently be understood as Zn rattling along the coordinative interaction. [ABSTRACT FROM AUTHOR]

Topological phononics, a fascinating frontier in condensed matter physics, holds great promise for advancing energy‐related applications. Topologically nontrivial phonons typically possess gapless edge or surface states. These exotic states of lattice vibrations, characterized by their nontrivial topology, offer unique opportunities for manipulating and harnessing energy transport. The exploration of topological phonons opens new avenues in understanding and controlling thermal transport properties, with potential applications in fields such as thermoelectric materials, phononic devices, and waste heat recovery. Here, an overview of concepts such as Berry curvature and topological invariants, along with the applications of phonon tight‐binding method and nonequilibrium Green's function method in the field of topological phononics is provided. This review encompasses the latest research progress of various topological phonon states within crystalline materials, including topological optical phonons, topological acoustical phonons, and higher‐order topological phonons. Furthermore, the study delves into the prospective applications of topological phonons in the realm of thermoelectric conversion, focusing on aspects like size effects and symmetry engineering. [ABSTRACT FROM AUTHOR]

The thermoelectric properties of Bi 0.5 Sb 1.5 Te 3 synthesized through the low-temperature liquid phase sintering (LPS) method can be significantly improved by employing a synergistic approach. During the heat treatment, excess Te undergoes self-swelling under optimal sintering pressure, facilitating the slip of matrix grains perpendicular to the applied pressure and subsequent recrystallization, leading to enhanced electrical properties. Building upon this basis, the heightened Seebeck coefficient and power factor of the thermoelectric matrix stem from the incorporation of 0.6 vol% B 4 C nanoparticles. Simultaneously, lattice thermal conductivity experiences notable suppression due to enhanced phonon scattering induced by additional interfaces, defects, and second-phase. Lastly, a markedly improved maximum ZT value of 1.30 at 333 K is achieved when the volume percentage of B 4 C nanoparticles is 0.6 vol%, representing a remarkable 23% enhancement compared to the untreated sample. These results indicate that the LPS method, coupled with the enhanced second nanophase scattering mechanism, is beneficial to enhancing the thermoelectric properties of Bi 2 Te 3 -based materials. [Display omitted] [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]

Organic molecule‐doped n‐type single‐walled carbon nanotube (SWCNT) networks are promising candidates for advanced energy applications, such as flexible thermoelectrics and photovoltaics. Yet charge transport in n‐type SWCNTs is limited by two factors: i) charge localization impeding inter‐tube transport caused by disordered mesostructure of randomly oriented SWCNTs and ii) reduction of charge carrier concentration driven by oxidation. Herein, studied the relationship between the mesostructure and thermoelectric properties of n‐type SWCNTs obtained by surfactant‐functionalization and polymer‐dopant grafting. Surprisingly, the electrical conductivity of the polymer‐doped SWCNTs keeps increasing with increasing polymer content, even after the saturation of carrier concentration, resulting in 12x higher conductivity on polymer‐doping compared to surfactant‐functionalization. While hopping transport typically dominates in disordered systems, it is shown that a bridging effect from the polymer causes unusual band‐like conduction in polymer‐doped SWCNTs. Additionally, since surfactants are essential to prevent oxidation and retain n‐type over a long duration, shows that SWCNTs obtained through a dual‐functionalization strategy using both polymer‐dopant and surfactant, demonstrates a long‐term stable high n‐type thermoelectric power factor, when the surfactant amount is carefully controlled. Besides thermoelectrics, the findings are of general interest to developing stable and conductive n‐type SWCNTs for various energy and electronic applications. [ABSTRACT FROM AUTHOR]