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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]

Despite more than seven decades of active research and development in thermoelectricity, the accurate measurement of the thermoelectric (TE) properties of bulk materials has remained a challenge, mainly because of the strong interrelation between thermal and electrical phenomena. This work highlights practical advancements in methods and instrumentation dedicated to the simultaneous measurements of TE properties such as the Seebeck coefficient (S), the thermal (κ), and electrical (σ) conductivities and the dimensionless TE figure of merit ZT = S2σT/κ. The accuracy of a Harman based approach, as implemented by the ZT-Scanner (TEMTE Inc.), applicable to the simultaneous measurement of the above TE properties, has been made possible by a self-contained calibration procedure, which is based on the availability of two samples of the same homogeneous material having different shape factors. It is of practical importance that this approach provides a simple procedure to obtain the calibration for the figure of merit ZT and the thermal conductivity in the temperature interval from 300 to 720 K. In addition, we show that a simplified Harman setup with no thermocouples attached to the sample can also be used for self-contained calibrated ZT measurements. It is concluded that the implemented steady-state approach decreases the relative error down to 1%–2% for ZT measurements and can be recommended for most applications not involving dynamical behavior. In particular, it is proposed that self-generated calibration samples can critically increase the quality and ease of comparison of TE measurements if they are adopted by the TE community. [ABSTRACT FROM AUTHOR]

In order to explore the interplay among heat, charge, and spin, we investigate the spin-related thermoelectricity of a hybrid double quantum dot Aharonov–Bohm interferometer with Rashba spin–orbit coupling (RSOC). Interestingly, the nonzero RSOC phase difference can induce significant spin-dependent thermoelectric transport. Not only can the strong violation of the Wiedemann-Franz law be obtained, but also a pure spin-Seebeck effect can be produced, which may serve as a pure spin-current generator. The influence of system parameters on thermoelectric coefficients (especially for spin counterparts) are analyzed in detail, and the underlying physics is further elucidated. Furthermore, the spin figure of merit can be much larger than the charge one, which, thus, provides a realistic possibility of engineering spin thermoelectric devices with high performance. These results obtained may be of interest for developing spin thermoelectric devices in the field of spin caloritronics. [ABSTRACT FROM AUTHOR]

Microstructures and thermoelectric properties of porous Ca 3 Co 4 O 9 ceramics were investigated, which were prepared by tert-butanol alcohol (TBA)-based freeze casting method. The honeycomb-like porous Ca 3 Co 4 O 9 ceramic presented an average pore diameter of 2.5 μm and the porosity of 65 %. The excellent low total thermal conductivity of 0.354 W (m K)−1 was obtained along the parallel channel direction, which was attributed to the oriented pores and isolated pores dispersed in ceramics matrix. The compositing thermal conductivity behavior of porous Ca 3 Co 4 O 9 ceramics was jointly regulated by the parallel and Maxwell-Eucken (ME-1) models. The ZT value reached 0.37 at 1073 K. This work provides an effective strategy to improve thermoelectric properties of oxides thermoelectric ceramics, which can complete the decoupling of electrical and thermal properties. [ABSTRACT FROM AUTHOR]

With buildings representing a substantial portion of global energy consumption, exploring alternatives to traditional fossil fuel-based heating and cooling systems is critical. Thermoelectricity offers a promising solution by converting temperature differentials into electrical voltage or vice versa, enabling efficient indoor thermal regulation. This paper presents a comprehensive investigation into the integration of thermoelectric wall systems for sustainable building climate control through numerical simulations and experimental analyses. Numerical simulations using computational fluid dynamics (CFD) techniques were conducted to model fluid flow and heat transfer within the thermoelectric wall systems under various operating conditions. These simulations provided insights into the system's thermal behavior, which were validated through experimental setups designed to measure temperature differentials, airflow rates, and power consumption. The results showed that power consumption is directly correlated with electrical current, ranging from 0.19 W to 77.4 W as the current increased from 0.1 A to 2 A. Additionally, the heat absorbed by the system increased significantly with electrical current, by 706–1044%, depending on the air velocity. The thermal energy released from the hot side of the thermoelectric modules also rose substantially, ranging from 9850 to 5285% with increasing electrical current, and from 275 to 51% with higher air velocities. Moreover, increasing air velocity led to a 6.78–9.37% reduction in power consumption for currents between 0.1 A and 2 A. The coefficient of performance (COP) analysis revealed that optimizing both electrical current and air velocity is essential for maximizing system efficiency. While fan power consumption reduces COP at higher air velocities, neglecting fan power consumption results in COP improvements ranging from 6.5 × 10⁻⁴ to 49.0%. These findings highlight the potential of thermoelectric wall systems to enhance indoor comfort and energy efficiency in buildings. [ABSTRACT FROM AUTHOR]

Composites consisting of two nano-or molecular-scale components tend to exhibit newer properties or characterizations compared to the matrix material. However, they are extremely limited in thermoelectricity due to the difficulty of achieving an extremely homogeneous distribution of the material on such a small scale. In this paper, we successfully prepared a series of composite thermoelectric materials of Sr 0.9 La 0.1 Ti 0.85 Nb 0.15 O 3 /carbon nanotubes (CNTs, with contents of 0.5, 1.5, 2.5, and 5.0 wt%). Highly homogeneous dispersion of CNTs was observed in the strontium titanate oxide (SrTiO 3) matrix prepared via high-temperature and high-pressure (HPHT) synthesis due to the interaction between SrTiO 3 and multi-walled CNTs. The experimental results showed that CNTs were uniformly dispersed in the composite powders synthesized using the HPHT method. Meanwhile, the electrical conductivity increased linearly with the increase in the CNTs content. The power factor reached 684 μWm−1K−2 at 973K with 2.5 wt% CNTs composite concentration. This considerable enhancement is attributed to the increase in the charge carrier concentration as well as the higher electron mobility. In addition, the lattice thermal conductivity was suppressed due to enhanced Umklapp scattering. This ultimately leads to a thermoelectric figure of merit, zT , of 0.33 at 973 K. This work opens a new window on the thermoelectric properties of nanocomposite SrTiO 3 -based thermoelectric materials. [ABSTRACT FROM AUTHOR]

Skin‐like electronics research aiming to mimic even surpass human‐like specific tactile cognition by operating perception‐to‐cognition‐to‐feedback of stimulus to build intelligent cognition systems for certain imperceptible or inappreciable signals was so attractive. Herein, we constructed an all‐in‐one tri‐modal pressure sensing wearable device to address the issue of power supply by integrating multistage microstructured ionic skin (MM i‐skin) and thermoelectric self‐power staffs, which exhibits high sensitivity simultaneously. The MM i‐skin with multi‐stage "interlocked" configurations achieved precise recognition of subtle signals, where the sensitivity reached up to 3.95 kPa−1, as well as response time of 46 ms, cyclic stability (over 1500 cycles), a wide detection range of 0–200 kPa. Furthermore, we developed the thermoelectricity nanogenerator, piezoelectricity nanogenerator, and piezocapacitive sensing as an integrated tri‐modal pressure sensing, denoted as P‐iskin, T‐iskin, and C‐iskin, respectively. This multifunctional ionic skin enables real‐time monitoring of weak body signals, rehab guidance, and robotic motion recognition, demonstrating potential for Internet of things (IoT) applications involving the artificial intelligence‐motivated sapiential healthcare Internet (SHI) and widely distributed human‐machine interaction (HMI). [ABSTRACT FROM AUTHOR]

There is still a lack of effective lubrication condition monitoring methods in the field of diesel engines. The paper proposes a novel thermoelectric approach to divide the lubrication state of bearings. First, the generation mechanism of thermoelectric potential on bearings is clarified. Then, both experimental and simulation studies are done, and a strong correlation between lubrication and thermoelectric potential is shown. The film thickness and temperature are further confirmed as significant factors influencing thermoelectric potential. Generally, the thermoelectric potential increases with temperature. However, a small film thickness ratio (when the film thickness ratio is less than 4) will suppress the thermoelectric potential. Three typical lubrication states of bearings are distinguished through thermoelectric potential and supported by the Stribeck curve results. Moreover, the significant influence of lubrication on the bearing is confirmed through the analysis of surface morphology and composition. [ABSTRACT FROM AUTHOR]

A theoretical prediction of the contribution to the thermo-electromotive force (thermo-EMF) of a thermocouple due to the minority charge carriers in both legs is presented. This prediction is made on the assumption that, at any time, the electrical conductivity of the majority charge carriers σ M remains very large compared to the electrical conductivity of the minority carriers σ m ( σ M ≫ σ m ). The expression has also been analyzed in order to find strategies to reduce its negative impact on the thermo-EMF of the thermocouple. Finally, calculations were carried out in the case of the thermocouple made of silicon thermoelements. The results show that the presence of minority carriers in the thermocouple legs can either positively or negatively affect the generated thermo-EMF. Whenever the contribution is negative, its magnitude may be reduced by widening the bandgap of the N-type leg and/or narrowing that of the p-type leg, adjusting the length of the legs, or intensifying recombinations on the surfaces of the P-type leg [ABSTRACT FROM AUTHOR]

I‐V‐VI2/IV‐VI compounds and their alloys are of great interest in the field of thermoelectricity due to their unique high‐symmetry crystal structures and unexpectedly low thermal conductivity, which is closely related to the off‐centering effect in the cubic lattice. However, the influence of such an effect on thermal transport across different temperatures remains largely elusive. Herein, using in situ pair distribution function analysis, it is directly observed that the sustained low thermal conductivity in n‐type (AgBiSe2)1‐x(PbS)x alloys stem from the dynamic intelligent switching of local structural distortions over wide temperature windows for the first time. Under ambient conditions, the local off‐centering of central atoms dominates the phonon scattering, while at high temperatures, the geometrical configuration of the ligands predominantly modulates thermal conductivity due to lattice expansion and diminished cation off‐centering. The complementary synergistic effect leads to an ultralow thermal conductivity (<0.64 W m−1 K−1) for (AgBiSe2)0.65(PbS)0.35 across the entire working temperature range and yields a lattice thermal conductivity of only 0.33 W m−1 K−1 at 800 K approaching the glass limit. Atomic‐scale insights into the thermal conductivity mechanism of I‐V‐VI2/IV‐VI alloys provide important guidance for designing high‐efficiency thermoelectric materials over broad operational temperature ranges. [ABSTRACT FROM AUTHOR]

The possible contribution of phonon drag effect to the thermoelectrically sustained potential of a heated nanoisland on a semiconductor surface was estimated in a first principal consideration. We regarded electrons and phonons as interacting particles, and the interaction cross-section was derived from the basic theory of semiconductors. The solution of the equation of motion for average electrons under the simultaneous action of phonon drag and electric field gave the distributions of phonon flux, density of charge carriers and electric potential. Dimensional suppression of thermal conductance and electron-phonon interaction were accounted for but found to be less effective than expected. The developed model predicts the formation of a layer with a high density of charge carriers that is practically independent of the concentration of dopant ions. This layer can effectively intercept the phonon flow propagating from the heated nanoisland. The resulting thermoEMF can have sufficient magnitudes to explain the low-voltage electron emission capability of nanoisland films of metals and sp2-bonded carbon, previously studied by our group. The phenomenon predicted by the model can be used in thermoelectric converters with untypical parameters or in systems for local cooling. [ABSTRACT FROM AUTHOR]

Abstract With buildings representing a substantial portion of global energy consumption, exploring alternatives to traditional fossil fuel-based heating and cooling systems is critical. Thermoelectricity offers a promising solution by converting temperature differentials into electrical voltage or vice versa, enabling efficient indoor thermal regulation. This paper presents a comprehensive investigation into the integration of thermoelectric wall systems for sustainable building climate control through numerical simulations and experimental analyses. Numerical simulations using computational fluid dynamics (CFD) techniques were conducted to model fluid flow and heat transfer within the thermoelectric wall systems under various operating conditions. These simulations provided insights into the system’s thermal behavior, which were validated through experimental setups designed to measure temperature differentials, airflow rates, and power consumption. The results showed that power consumption is directly correlated with electrical current, ranging from 0.19 W to 77.4 W as the current increased from 0.1 A to 2 A. Additionally, the heat absorbed by the system increased significantly with electrical current, by 706–1044%, depending on the air velocity. The thermal energy released from the hot side of the thermoelectric modules also rose substantially, ranging from 9850 to 5285% with increasing electrical current, and from 275 to 51% with higher air velocities. Moreover, increasing air velocity led to a 6.78–9.37% reduction in power consumption for currents between 0.1 A and 2 A. The coefficient of performance (COP) analysis revealed that optimizing both electrical current and air velocity is essential for maximizing system efficiency. While fan power consumption reduces COP at higher air velocities, neglecting fan power consumption results in COP improvements ranging from 6.5 × 10⁻⁴ to 49.0%. These findings highlight the potential of thermoelectric wall systems to enhance indoor comfort and energy efficiency in buildings.

[Display omitted] • Quaternary Ag 2 SbBiSe 4 NCs are synthesized by a colloidal synthesis route. • Ag 2 SbBiSe 4 has a cubic crystal structure and a wide band gap. • Ag 2 SbBiSe 4 maintains low lattice thermal conductivity of ca. 0.34 W m−1K−1. • Modulation doping through Sn NCs is used to tune the TE performance of Ag 2 SbBiSe 4. • A maximum ZT value of 0.64 at 760 K and a high Vickers Hardness of ~185 Hv are obtained. Materials with low intrinsic thermal conductivity are essential for the development of high-performance thermoelectric devices. At the same time, the solution processing of these materials may enable the cost-effective production of the devices. Herein, we detail a high-yield and scalable colloidal synthesis route to produce Ag 2 SbBiSe 4 nanocrystals (NCs) using amine-thiol-Se chemistry. The quaternary chalcogenide material is consolidated by a rapid hot-press maintaining the cubic crystalline structure. Transport measurements confirm that n -type Ag 2 SbBiSe 4 exhibits an inherently ultralow lattice thermal conductivity of ca. 0.34 W m−1K−1 at 760 K. Moreover, a modulation doping strategy based on the blending of semiconductor Ag 2 SbBiSe 4 and metallic Sn NCs is demonstrated to control the charge carrier concentration in the final composite material. The introduction of Sn nanodomains additionally blocks phonon propagation thus contributing to reducing the thermal conductivity of the final material. Ultimately, a peak thermoelectric figure of merit value of 0.64 at 760 K is achieved for n -type Ag 2 SbBiSe 4 -Sn nanocomposites that also demonstrate a notable Vickers hardness of 185 HV. [ABSTRACT FROM AUTHOR]

The energy transported by the electric current that circulates a thermoelectric element (TE) varies with position due to the Joule and Thomson effects. The Thomson effect may enhance or compensate the Joule effect. A method for measuring the Thomson coefficient of a TE is presented. This method is based on the total compensation of the Joule and Thomson effects. The electric current then flows without delivering power to the TE or absorbing power from it. For a TE, the global Thomson/Joule compensation ratio Φ ¯ T / J is defined as the ratio of the power absorbed by the current due to the Thomson effect and the power delivered by the current to the TE due to the Joule effect. It can be expressed as Φ ¯ T / J = I 0 / I , where I is the electric current and I 0 is the zero-power current, a quantity that is proportional to the average Thomson coefficient. When I = I 0 , the Thomson effect exactly compensates the Joule effect and the net power delivered by the current to the TE is zero. Since the power delivered by the current is related to the temperature distribution, temperature measurements for currents around I 0 can be used as the basis for a measurement technique of the Thomson coefficient. With varying current, the difference between the temperature at the center of the TE and the mean temperature between its extremes reverses its sign at the zero-power current, I = I 0 . This observation suggests the possibility of measuring the Thomson coefficient, but a quantitative analysis is needed. With calculations using the constant transport coefficients model for B i 2 T e 0.94 S e 0.06 3   and B i 0.25 S b 0.75 2 T e 3 , it is theoretically shown that a null temperature detector with a sensitivity of the order of 1 mK allows for the accurate determination of the Thomson coefficient. [ABSTRACT FROM AUTHOR]

This paper presents a novel waste-heat-powered, wireless, and battery-less Industrial Internet of Things (IIoT) device designed for predictive maintenance in Industry 4.0 environments. With a focus on real-time quality data, this device addresses the limitations of current battery-operated IIoT devices, such as energy consumption, transmission range, data rate, and constant quality of service. It is specifically developed for heat-intensive industries (e.g., iron and steel, cement, petrochemical, etc.), where self-heating nodes, low-power processing platforms, and industrial sensors align with the stringent requirements of industrial monitoring. The presented IIoT device uses thermoelectric generators based on the Seebeck effect to harness waste heat from any hot surface, such as pipes or chimneys, ensuring continuous power without the need for batteries. The energy that is recovered can be used to power devices using mid-range wireless protocols like Bluetooth 5.0, minimizing the need for extensive in-house wireless infrastructure and incorporating light-edge computing. Consequently, up to 98% of cloud computation efforts and associated greenhouse gas emissions are reduced as data is processed within the IoT device. From the environmental perspective, the deployment of such self-powered IIoT devices contributes to reducing the carbon footprint in energy-demanding industries, aiding their digitalization transition towards the industry 5.0 paradigm. This paper presents the results of the most challenging energy harvesting technologies based on an all-silicon micro thermoelectric generator with planar architecture. The effectiveness and self-powering ability of the selected model, coupled with an ultra-low-power processing platform and Bluetooth 5 connectivity, are validated in an equivalent industrial environment to monitor vibrations in an electric machine. This approach aligns with the EU's strategic objective of achieving net zero manufacturing capacity for renewable energy technologies, enhancing its position as a global leader in renewable energy technology (RET). [ABSTRACT FROM AUTHOR]

This work aims to develop a prototype for autonomously monitoring highway weather conditions using thermoelectric energy. The prototype utilizes solar thermal energy, heat absorbed by the asphalt and soil heat to generate, convert, manage, and store energy. The study investigates the optimal functioning of the thermoelectric generator, including utilizing the soil as a heat sink and incorporating passive thermal control devices like heat pipes. A commercial ultra-low power converter model LTC3108 was experimentally tested for efficient energy conversion. The monitoring system is designed to acquire readings from sensors measuring relevant climate parameters such as temperature, atmospheric pressure, and humidity, focusing on ultra-low power characteristics. The acquired data is transmitted via LoRa technology to a server for processing and analysis. The prototype generated 286.24 J of energy with a maximum temperature gradient of 4.25 ºC in the thermoelectric generator. The energy cost of transmitting a 40-byte message through the LoRaWAN module was 0.625 J. The proposed climate data acquisition circuit had a theoretical consumption of 17.69 J. Experimental tests with the LTC3108 converter, and a 0.22 F supercapacitor demonstrated successful data transmission. This work provides a solid foundation for future studies utilizing thermoelectric energy in highway applications, resulting in a prototype suitable for real-world road scenarios. [ABSTRACT FROM AUTHOR]

Developing cost‐effective and high‐performance thermoelectric (TE) materials to assemble efficient TE devices presents a multitude of challenges and opportunities. Cu3SbSe4 is a promising p‐type TE material based on relatively earth abundant elements. However, the challenge lies in its poor electrical conductivity. Herein, an efficient and scalable solution‐based approach is developed to synthesize high‐quality Cu3SbSe4 nanocrystals doped with Pb at the Sb site. After ligand displacement and annealing treatments, the dried powders are consolidated into dense pellets, and their TE properties are investigated. Pb doping effectively increases the charge carrier concentration, resulting in a significant increase in electrical conductivity, while the Seebeck coefficients remain consistently high. The calculated band structure shows that Pb doping induces band convergence, thereby increasing the effective mass. Furthermore, the large ionic radius of Pb2+ results in the generation of additional point and plane defects and interphases, dramatically enhancing phonon scattering, which significantly decreases the lattice thermal conductivity at high temperatures. Overall, a maximum figure of merit (zTmax) ≈ 0.85 at 653 K is obtained in Cu3Sb0.97Pb0.03Se4. This represents a 1.6‐fold increase compared to the undoped sample and exceeds most doped Cu3SbSe4‐based materials produced by solid‐state, demonstrating advantages of versatility and cost‐effectiveness using a solution‐based technology. [ABSTRACT FROM AUTHOR]

Developing cost‐effective and high‐performance thermoelectric (TE) materials to assemble efficient TE devices presents a multitude of challenges and opportunities. Cu3SbSe4 is a promising p‐type TE material based on relatively earth abundant elements. However, the challenge lies in its poor electrical conductivity. Herein, an efficient and scalable solution‐based approach is developed to synthesize high‐quality Cu3SbSe4 nanocrystals doped with Pb at the Sb site. After ligand displacement and annealing treatments, the dried powders are consolidated into dense pellets, and their TE properties are investigated. Pb doping effectively increases the charge carrier concentration, resulting in a significant increase in electrical conductivity, while the Seebeck coefficients remain consistently high. The calculated band structure shows that Pb doping induces band convergence, thereby increasing the effective mass. Furthermore, the large ionic radius of Pb2+ results in the generation of additional point and plane defects and interphases, dramatically enhancing phonon scattering, which significantly decreases the lattice thermal conductivity at high temperatures. Overall, a maximum figure of merit (zTmax) ≈ 0.85 at 653 K is obtained in Cu3Sb0.97Pb0.03Se4. This represents a 1.6‐fold increase compared to the undoped sample and exceeds most doped Cu3SbSe4‐based materials produced by solid‐state, demonstrating advantages of versatility and cost‐effectiveness using a solution‐based technology. [ABSTRACT FROM AUTHOR]

Self‐powered photodetectors with dual‐polarity response have great advantages in processing complex light information that is proven to be applied in switchable light imaging, optical communication, and spectral band distinction. Here, a novel strategy for designing self‐powered photodetectors by introducing the double symmetric Schottky junctions at the semiconductor‐metal interfaces is proposed, which guarantees the linear response characteristic and dominates the transfer of photogenerated carriers without external bias. Narrow bandgap semiconductor SnTe is employed as the photosensitive material. The bandgap is characterized to be 126 meV, showing great potential for wide spectrum response. As the consequence of selective excitation of unilateral Schottky junction and switching of electric field polarity, the device obtains a dual‐polarity photoresponse, which can be tuned from −14.8 to 13.5 µV. Moreover, an ultra‐broadband photoresponse from near‐infrared 808 nm to far infrared 10.6 µm is achieved with deep exploration of the working mechanism. The synergistic effect of photo thermoelectricity and photoconductivity created a high photoresponsivity of 0.35 mV W−1 excited by 10.6 µm at room temperature. This work provides a novel design strategy for self‐powered photodetectors with a dual‐polarity powered principle, which can take full advantage of the directivity of the photoresponse to identify optical information. [ABSTRACT FROM AUTHOR]

The stunning thermoelectric behavior of inorganic/organic hybrids and the lack of information on screen-printed flexible thermoelectric generators based on Cu 3 Se 2 and Polyaniline for low-temperature applications have motivated this work. The synergic influence of various acid dopants, concentration, and annealing temperature of polyaniline on the power density of Cu 3 Se 2 /PANI ink-based flexible thermoelectric generator is explored. The presence of 1.5 wt% of H 2 SO 4 -PANI, annealed at 60 °C, decreased the bandgap and electrical resistance of Cu 3 Se 2 by 11.96 % and 29.4 %, respectively. As a result, an increase of 46.06 % in the Seebeck coefficient and 242 % in the power output is achieved, which is many folds higher than the few reported works using novel materials. In addition, the Cu 3 Se 2 /H 2 SO 4 -PANI ink-based flexible thermoelectric generator with eight legs exhibited a maximum power output, power density, and power factor of 25.69 nW, 23.79 mW/m2, and 0.77 nW/m2K2 at ΔT = 100 °C, respectively under external load. [ABSTRACT FROM AUTHOR]

Using density functional theory combined with the first principles calculation method of non-equilibrium Green's function (NEGF-DFT), we studied the thermoelectric (TE) characteristics of one-dimensional γ-graphdiyne nanoribbons (γ-GDYNRs). The study found that the thermal conductivity of γ-GDYNRs has obvious anisotropy. At the same temperature and geometrical size, the lattice thermal conductivity of zigzag-edged γ-graphdiyne nanoribbons (γ-ZGDYNRs) is much lower than that of armchair-edged γ-graphdiyne nanoribbons (γ-AGDYNRs). We disclose the underlying mechanism for this intrinsic orientation. That is, γ-AGDYNRs have more phonon dispersion over the entire frequency range. Furthermore, the orientation dependence increases when the width of the γ-GDYNRs decreases. These excellent TE properties allow armchair-edged γ-graphdiyne nanoribbons with a planar width of 1.639 nm (γ-Z(2)GDYNRs) to have a higher power factor and lower thermal conductivity, ultimately resulting in a significantly higher TE conversion rate than other γ-GDYNR structures. [ABSTRACT FROM AUTHOR]

Bi 2 Te 3 -based crystal ingots produced by zone melting (ZM) are the most widely used materials to manufacture commercial thermoelectric (TE) devices. However, the poor mechanical properties of such crystalline materials limit the production of small-scale devices. While processability can be improved by powder metallurgy (PM), it also leads to the deterioration of the TE properties due to the donor-like effect of the introduced defects and grain boundaries. Thus, additional efforts towards re-optimizing doping are required. Here, we report a PM method to improve the mechanical properties of Bi 2 Te 3 -based TE materials through the crushing and hot pressing of Bi 2 Te 3 ingots obtained by ZM. Besides, we demonstrate the TE properties of n-type Bi 2 Te 2.7 Se 0.3 (BTS) to be remarkably improved by Cu doping, which enables optimization of the carrier concentration and enhances phonon scattering at heterointerphases thus increasing the Seebeck coefficient and reducing thermal conductivity. Overall, optimized materials reach dimensionless TE figures of merit (ZT) up to 1.16 at 408 K, i.e. 45% higher than that of state-of-the-art BTS, and an average ZT value of 1.08 in the temperature range of 300–473 K. [ABSTRACT FROM AUTHOR]

High‐field superconductors are characterized by a spin splitting of the density of states, giving rise to spin transport phenomena. This includes spin‐polarized tunneling, spin‐dependent thermoelectric effects, long‐range quasiparticle spin transport, and spin‐dependent coupling of supercurrents and quasiparticles. This review gives a brief overview of the theory background, recent experimental progress in the field, and an outlook on open problems and possible applications. [ABSTRACT FROM AUTHOR]

Understanding thermal transport at the submicron scale is crucial for engineering applications, especially in the thermal management of electronics and tailoring the thermal conductivity of thermoelectric materials. At the submicron scale, the macroscopic heat diffusion equation is no longer valid and the phonon Boltzmann transport equation (BTE) becomes the governing equation for thermal transport. However, previous thermal simulations based on the phonon BTE have two main limitations: relying on empirical parameters and prohibitive computational costs. Therefore, the phonon BTE is commonly used for qualitatively studying the non-Fourier thermal transport phenomena of toy problems. In this work, we demonstrate an ultra-efficient and parameter-free computational method of the phonon BTE to achieve quantitatively accurate thermal simulation for realistic materials and devices. By properly integrating the phonon properties from first-principles calculations, our method does not rely on empirical material properties input. It can be generally applicable for different materials and the predicted results can match well with experimental results. Moreover, by developing a suitable ensemble of advanced numerical algorithms, our method exhibits superior numerical efficiency. The full-scale (from ballistic to diffusive) thermal simulation of a 3-dimensional fin field-effect transistor with 13 million degrees of freedom, which is prohibitive for existing phonon BTE solvers even on supercomputers, can now be completed within two hours on a single personal computer. Our method makes it possible to achieve the predictive design of realistic nanostructures for the desired thermal conductivity. It also enables accurately resolving the temperature profiles at the transistor level, which helps in better understanding the self-heating effect of electronics. [ABSTRACT FROM AUTHOR]

Heusler compounds stand as a versatile class of intermetallics with extraordinary electrical, magnetic, and thermoelectric properties that render them indispensable in various applications. This study delves deeply into the mechanical, dynamical, electronic, magnetic, and transport characteristics of Mn 2 CoGe and Mn 2 CoSb compounds. Both compounds display mechanical stability, ionic bonding, and a ductile nature. The positive phonon frequencies further affirm their dynamical stability. Moving to the electronic structure calculations, our assessments encompass magnetic moment, band structure, and density of states, highlighting the distinctive half-metallic characteristics inherent in these compounds. Transport coefficient calculations for both spin channels demonstrate the compounds' relative constancy in terms of Seebeck coefficient and electrical conductivity despite temperature fluctuations. The observed spin polarisation and thermoelectric response underscore the promising suitability of these compounds for future applications in spintronics and thermoelectrics. While the achieved maximum thermoelectric figure of merit value of 0.2 holds potential for their thermoelectric capabilities, further experimental validations are imperative for a comprehensive evaluation. [ABSTRACT FROM AUTHOR]

This paper reports first-principles calculations on nanosheets of Ge–Sb–Te compounds, namely Sb 2 Te 3 , GeSb 2 Te 4 and Ge 2 Sb 2 Te 5 under two crystalline atomic stakings S1 and S2. Sb 2 Te 3 , GeSb 2 Te 4 and Ge 2 Sb 2 Te 5 -S1 are semiconductors with a narrow band gap ranging between 0.7 and 0.74 eV as evaluated with the HSEsol functional. The transport properties have been investigated by Boltzmann transport theory together with deformation potential theory. The strain effects on their electronic and thermoelectric properties as well as on their dynamical properties have been investigated. A valence band convergence is found in the equilibrium structures, which is an efficient approach to improve the thermoelectric performance of materials. Sb 2 Te 3 , GeSb 2 Te 4 and Ge 2 Sb 2 Te 5 -S1 possess high TE performance in a wide range of temperature, and the highest values of zT are 2.94, 2.63 and 2.27, respectively. [ABSTRACT FROM AUTHOR]

A comprehensive study of the thermoelectric properties of CuCr0.99Ln0.01S2 (Ln = La…Lu) disulfides was carried out in a temperature range of 300 to 740 K. The temperature dependencies of the Seebeck coefficient, electrical resistivity, and thermal conductivity were analyzed. It was found that the cationic substitution of chromium with lanthanides in the crystal structure of layered copper–chromium disulfide, CuCrS2 resulted in notable changes in the thermoelectric performance of CuCr0.99Ln0.01S2. The cationic substitution led to an increase in the Seebeck coefficient and electrical resistivity and a thermal conductivity decrease. The highest values of the thermoelectric figure of merit and power factor corresponded to the praseodymium-doped sample and an initial CuCrS2-matrix at 700–740 K. The cationic substitution with lanthanum, cerium, praseodymium, samarium, and terbium allowed for an enhancement of the thermoelectric performance of the initial matrix at a temperature range below 600 K. The cationic substitution of CuCrS2 with lanthanum and praseodymium ions appeared to be the most promising approach for increasing the thermoelectric performance of the initial matrix.

We present experimental evidence of a thermoelectric effect at the interface between two liquid metals. Using superimposed layers of mercury and gallium in a cylindrical vessel operating at room temperature, we provide a direct measurement of the electric current generated by the presence of a thermal gradient along a liquid-liquid interface. At the interface between two liquids, temperature gradients induced by thermal convection lead to a complex geometry of electric currents, ultimately generating current densities near boundaries that are significantly higher than those observed in conventional solid-state thermoelectricity. When a magnetic field is applied to the experiment, an azimuthal shear flow, exhibiting opposite circulation in each layer, is generated. Depending on the value of the magnetic field, two different flow regimes are identified, in good agreement with a model based on the spatial distribution of thermoelectric currents, which has no equivalent in solid systems. Finally, we discuss various applications of this effect, such as the efficiencyofliquid metal batteries. [ABSTRACT FROM AUTHOR]

A wearable energy harvester (EH) incorporating a face mask with a thermoelectric generator is demonstrated. The function of this device is to generate electrical power from the heat produced by the human body, particularly breath, with the specific aim of powering wearable sensor applications. A prototype was built using a commercially available N95 face mask, a thermoelectric generator, and a heatsink. The performance of this EH device was assessed using experimental and numerical methodologies. The experimentally tested power output of the prototype was found to be ≈100 µW, with a corresponding power density of ≈30 µW/cm3, for a temperature difference of 7°C. [ABSTRACT FROM AUTHOR]

Carbon nanocoils (CNCs) have been discovered and studied for years. Its good electrical conductivity and low lattice thermal conductivity suggest the application potential in thermoelectricity, which was studied for the first time in this work. Individual CNCs were suspended between two substrates with electrical heaters to create the desired temperature differences. Employing a transient electro-thermal technique, the thermoelectric, electrical, and heat transport properties of CNCs from 298 to 343 K before and after in situ Joule annealing were characterized simultaneously. CNCs exhibit asymmetric thermoelectric responses, with average Seebeck coefficients along the two length directions of 1.5 and 0.9 μV/K. This asymmetry results from different bandgaps along the growth direction, and the small Seebeck coefficient results from strong mixed electrical conductivity. The Fermi energy and optical bandgap of CNCs were measured to be 11.2 and 58.2 meV, respectively, with a small hole–electron conductivity ratio (1.36). The Seebeck coefficient shows a negative correlation with the electrical conductivity, while the thermal conductivity shows no observable correlation with them, hovering around 8.3 W/m K at room temperature. Doping may be an effective strategy to increase the Seebeck coefficient and electrical conductivity while decreasing the thermal conductivity for improved thermoelectric conversion. In addition, a flexible nanothermocouple based on two intertwined single CNCs was developed, which shows excellent response to thermal excitation. [ABSTRACT FROM AUTHOR]

Thermoelectric materials convert heat into electricity, with a broad range of applications near room temperature (RT). However, the library of RT high‐performance materials is limited. Traditional high‐temperature synthetic methods constrain the range of materials achievable, hindering the ability to surpass crystal structure limitations and engineer defects. Here, a solution‐based synthetic approach is introduced, enabling RT synthesis of powders and exploration of densification at lower temperatures to influence the material's microstructure. The approach is exemplified by Ag2Se, an n‐type alternative to bismuth telluride. It is demonstrated that the concentration of Ag interstitials, grain boundaries, and dislocations are directly correlated to the sintering temperature, and achieve a figure of merit of 1.1 from RT to 100 °C after optimization. Moreover, insights into and resolve Ag2Se's challenges are provided, including stoichiometry issues leading to irreproducible performances. This work highlights the potential of RT solution synthesis in expanding the repertoire of high‐performance thermoelectric materials for practical applications. [ABSTRACT FROM AUTHOR]

Heat engines are key devices that convert thermal energy into usable energy. Strong thermoelectricity, at the basis of electrical heat engines, is present in superconducting spin tunnel barriers at cryogenic temperatures where conventional semiconducting or metallic technologies cease to work. Here we realize a superconducting spintronic heat engine consisting of a ferromagnetic insulator/superconductor/insulator/ferromagnet tunnel junction (EuS/Al/AlOx/Co). The efficiency of the engine is quantified for bath temperatures ranging from 25 mK up to 800 mK, and at different load resistances. Moreover, we show that the sign of the generated thermoelectric voltage can be inverted according to the parallel or anti-parallel orientation of the two ferromagnetic layers, EuS and Co. This realizes a thermoelectric spin valve controlling the sign and strength of the Seebeck coefficient, thereby implementing a thermoelectric memory cell. We propose a theoretical model that allows describing the experimental data and predicts the engine efficiency for different device parameters. An electrical heat engine has been realized at sub-Kelvin temperatures. It consists of a superconducting spin-selective tunnel junction of EuS/Al/AlOx/Co. The efficiency of the engine is quantified for different magnetic configurations. [ABSTRACT FROM AUTHOR]

A comprehensive study of the thermoelectric properties of CuCr0.99Ln0.01S2 (Ln = La...Lu) disulfides was carried out in a temperature range of 300 to 740 K. The temperature dependencies of the Seebeck coefficient, electrical resistivity, and thermal conductivity were analyzed. It was found that the cationic substitution of chromium with lanthanides in the crystal structure of layered copper–chromium disulfide, CuCrS2 resulted in notable changes in the thermoelectric performance of CuCr0.99Ln0.01S2. The cationic substitution led to an increase in the Seebeck coefficient and electrical resistivity and a thermal conductivity decrease. The highest values of the thermoelectric figure of merit and power factor corresponded to the praseodymium-doped sample and an initial CuCrS2-matrix at 700–740 K. The cationic substitution with lanthanum, cerium, praseodymium, samarium, and terbium allowed for an enhancement of the thermoelectric performance of the initial matrix at a temperature range below 600 K. The cationic substitution of CuCrS2 with lanthanum and praseodymium ions appeared to be the most promising approach for increasing the thermoelectric performance of the initial matrix. [ABSTRACT FROM AUTHOR]

Maximizing the power delivered by a thermoelectric generator (TEG) (with an internal resistance RTE) can be achieved by optimizing its design taking into account the external load (with a resistance of RL). In the present work, the evolution of the thermoelectric (TE) properties of the materials along the leg was considered. By considering a fixed heat rate on the hot side, the powers delivered by various TEGs were assessed by varying the length of the legs. After that, analytical approach was detailed based on the mathematical formulas governing the thermal and electrical transports. This approach revealed that the ratio m = RL/RTE is between the most commonly claimed values (1 and (1 + zT)1/2). Our variable properties model reveals that the optimal design requires lower cost than that considered by equaling RTE and RL (m = 1). This finding turns out to be more and more valid for materials which present a linear variation of temperature with position. [ABSTRACT FROM AUTHOR]

The research and management of Industry 4.0 increasingly relies on accurate real-time quality data to apply efficient algorithms for predictive maintenance. Currently, Low-Power Wide-Area Networks (LPWANs) offer potential advantages in monitoring tasks for predictive maintenance. However, their applicability requires improvements in aspects such as energy consumption, transmission range, data rate and constant quality of service. Commonly used battery-operated IIoT devices have several limitations in their adoption in large facilities or heat-intensive industries (iron and steel, cement, etc.). In these cases, the self-heating nodes together with the appropriate low-power processing platform and industrial sensors are aligned with the requirements and real-time criteria required for industrial monitoring. From an environmental point of view, the carbon footprint associated with human activity leads to a steady rise in global average temperature. Most of the gases emitted into the atmosphere are due to these heat-intensive industries. In fact, much of the energy consumed by industries is dissipated in the form of waste heat. With this scenario, it makes sense to build heat transformation collection systems as guarantors of battery-free self-powered IIoT devices. Thermal energy harvesters work on the physical basis of the Seebeck effect. In this way, this paper gathers the methodology that standardizes the modelling and simulation of waste heat recovery systems for IoT nodes, gathering energy from any hot surface, such as a pipe or chimney. The statistical analysis is carried out with the data obtained from two different IoT architectures showing a good correlation between model simulation and prototype behaviour. Additionally, the selected model will be coupled to a low-power processing platform with LoRaWAN connectivity to demonstrate its effectiveness and self-powering ability in a real industrial environment. [ABSTRACT FROM AUTHOR]

An ab initio characterization of the impact of tert‐Butyl isocyanate (C5H9NO${\rm C}_5{\rm H}_9{\rm NO}$) functionalization on TaS2${\rm TaS}_2$ lattice thermal conductivity is presented. Such a system has been previously synthetized and experimentally charachterized, showing that the incorporation of covalently bonded C5H9NO${\rm C}_5{\rm H}_9{\rm NO}$ on bulk TaS2${\rm TaS}_2$ leads to a dramatic in‐plane lattice thermal conductivity decrease by more than two orders of magnitudes. To elucidate these experimental findings, detailed calculations of the phonon dispersion relations and scattering rates in TaS2${\rm TaS}_2$ are performed. The analysis is addressed to discern the impact of inter‐layer covalently bonded C5H9NO${\rm C}_5{\rm H}_9{\rm NO}$ molecules on these phonon properties, providing insights into the underlying mechanisms of the observed thermal conductivity decrease. Present calculations provide evidence that the observed lattice thermal conductivity reduction is attributed to two effects: i)$i)$ the increase of inter‐layer separation and ii)$ii)$ the presence of low‐frequency molecular optical modes. The first inhibits specific Van der Waals quasi‐acoustic inter‐layer vibrational modes contributing as much as ≈55%$\approx \!\! 55\%$ in bulk TaS2${\rm TaS}_2$. The second effect dramatically decreases the phonon group velocities as a consequence of phonon‐crossing phenomena among low‐frequency molecular modes and TaS2${\rm TaS}_2$ acoustic modes, eventually leading to a strong reduction of all phonon lifetimes. [ABSTRACT FROM AUTHOR]

The conversion of heat into electricity using the thermoelectric effect is a crucial issue to tackle the ever-increasing global energy consumption. Cu 2 Se is one of the high-performance thermoelectric materials due to its liquid-like atomic structure, which minimizes the phonon-derived thermal conductivity. Nevertheless, the unambiguous atomic structure of the low-temperature phase, α -Cu 2 Se, remains controversial. By employing a combination of theoretical approaches including an evolutionary algorithm for structural searching, density functional theory, and lattice dynamics, the α -Cu 2 Se phase is proposed to crystalize in the dynamically stable triclinic Cu 2 Se structure (s.g. P1) which can be regarded as a monoclinic polymorph (s.g. P2 1 /c †) through slight distortion. The corresponding heat capacity (C V) and Debye temperature (Θ D) are 0.37 J/g K and 276 K, respectively, indicating low thermal conductivity in the material. The semiconducting P1 phase possesses an indirect gap of 1.0 eV. Additionally, based on the Boltzmann transportation theory, fundamental thermoelectric parameters around the transition temperature (300–500 K) are investigated. Beyond the semiconducting phase, a novel metallic phase identified as the triclinic P 1 ̄ phase is also discovered, exhibiting a two-dimensional (2D) crystal geometry. [ABSTRACT FROM AUTHOR]

Because there is a critical necessity to ensure the optimal operation of concentrated photovoltaic-thermoelectric (CPV-TE) systems, various optimization methods such as Paretosearch (PS), Multi-objective genetic algorithm (MOGA), and the hybrid Goal Attainment - Multi-objective genetic algorithm (GOAL-MOGA) are commonly employed. These approaches aim to enhance both the output power and energy efficiency of CPV-TE systems. By combining the Pareto fronts generated by MOGA and GOAL-MOGA, 19 distinct machine learning (ML) algorithms were trained. The findings demonstrate that the Artificial Neural Network (ANN) ML algorithm outperforms others, displaying an average prediction error of 0.0692% on the test dataset. In addition to its prediction capability, the ANN-based ML model can be viewed as an optimization model since it produces optimized outputs similar to those from MOGA and GOAL-MOGA. The ANN-based ML algorithm performs better when trained on a combined dataset from both MOGA and GOAL-MOGA compared to using either MOGA or GOAL-MOGA alone. To enhance the optimization capability of the ANN-based ML algorithm further, more Pareto fronts from other optimization techniques can be added. [ABSTRACT FROM AUTHOR]

Although orthorhombic GeSe is predicted to have an ultrahigh figure of merit, ZT ≈ 2.5, up to now, the highest experimental value is ≈0.2 due to the low carrier concentration (nH ≈ 1018 cm−3). Improving symmetry is an effective approach for enhancing the ZT of GeSe‐based materials. With Te‐alloying, Ge4Se3Te displays the two‐dimensional hexagonal structure and high nH ≈ 1.23 × 1021 cm−3. Interestingly, Ge4Se3Te transformed from the hexagonal into the rhombohedral phase with only ≈2% I–V–VI2‐alloying (I = Li, Na, K, Cu, Ag; V = Sb, Bi; VI = Se, Te). According to the calculated results of Ge0.82Ag0.09Bi0.09Se0.614Te0.386 single‐crystal grown via AgBiTe2‐alloying, it exhibits a higher valley degeneracy than the hexagonal Ge4Se3Te. For instance, AgBiTe2‐alloying induces a strong band convergence and band inversion effect, resulting in a significantly enhanced Seebeck coefficient and power factor with a similar nH from 17 µV K−1 and 0.63 µW cm−1 K−2 for pristine Ge4Se3Te to 124 µV K−1 and 5.97 µW cm−1 K−2 for 12%AgBiTe2‐alloyed sample, respectively. Moreover, the sharply reduced phonon velocity, nano‐domain wall structure, and strong anharmonicity lead to low lattice thermal conductivity. As a result, a record‐high average ZT ≈0.95 over 323–773 K with an excellent ZT ≈ 1.30 is achieved at 723 K. [ABSTRACT FROM AUTHOR]

The development of two-dimensional (2D) materials has received wide attention as a generation of optoelectronics, thermoelectric, and other applications. In this study, a novel 2D material, PbN, is proposed as an elemental method using the prototype of a recent reported nitride (J. Phys. Chem. C 2023, 127, 43, 21,006-21014). Based on first-principle calculations, the PbN monolayer is investigated as stable at 900 K, and the isotropic mechanical behavior is addressed by the Young's modulus and Poisson's ratio at 67.4 N m-1 and 0.15, respectively. The PbN monolayer also presents excellent catalytic performance with Gibbs free energy of 0.41 eV. Zero bandgap is found for the PbN monolayer, and it can be opened at about 0.128 eV by forming a heterostructure with CdO. Furthermore, the PbN/CdO is constructed by Van der Waals interaction, while the apparent potential drop and charge transfer are investigated at the interface. The PbN/CdO heterostructure also possesses excellent light absorption properties. The results provide theoretical guidance for the design of layered functional materials. [ABSTRACT FROM AUTHOR]

ZnO is one of the most promising mid-high temperature thermoelectric materials because of low cost, easy preparation and favorable chemical stability. Herein, the influence mechanism of Alkaline earth metal Ba doping on the thermoelectric properties of ZnO was studied. It is found that Ba doping can effectively improve the carrier mobility and electrical conductivity for that Ba doping can shorten the Zn–O bond and enhance the overlap and hybridization of electron orbitals. The electronic density of states of Zn and O is significantly enhanced. The highest power factor of ∼7.95 μWcm−1K−2 was obtained at 873 K, which is ∼1.4 times higher than that of the undoped sample. Due to the decrease of Young's modulus caused by Ba doping and the enhancement of phonon scattering of heavy element, the thermal conductivity decreases obviously in the whole temperature range. Ba doping enhanced the effect of phonon glass-electron crystal, and the ZT value of ∼0.345 was obtained at 873 K, which is ∼3.52 times as that of the pristine ZnO. The results indicated that alkaline earth metal doping is an effective way to improve the thermoelectric properties of ZnO functional materials. [ABSTRACT FROM AUTHOR]

This paper develops a thermoelectric (TE)–piezoelectric (PE) hybrid structure with the PE layer acting as both a support membrane and a sensor for the TE film for microelectronics applications. The TE and PE layers are assumed to be perfectly bonded mechanically and thermally but electrically shielded and insulated with each other. The thermo-electro-mechanical responses of the hybrid bilayer under the TE generator operation conditions are obtained, and the influence of the PE layer on the TE energy conversion efficiency is investigated. The numerical results for a Bi2Te3/PZT-5H bilayer structure show that large compressive stresses develop in both the PE and TE layers. With a decrease in the PE layer thickness, the magnitude of the maximum compressive stress in the PE layer increases whereas the maximum magnitude of the stress in the TE layer decreases. The numerical result of the TE energy conversion efficiency shows that increasing the PE layer thickness leads to lower energy conversion efficiencies. A nearly 40% reduction in the peak efficiency is observed with a PE layer of the same thickness as that of the TE layer. These results suggest that design of TE films with supporting/sensing membranes must consider both aspects of energy conversion efficiency and the thermomechanical reliability of both the TE and PE layers. [ABSTRACT FROM AUTHOR]