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We attempted to deposit a platinum (Pt) layer onto a tungsten trioxide (WO3) thin film (Pt/WO3). The Pt layer deposited on WO3 was oxidized by calcining Pt/WO3 in air to form PtOx/WO3. An n-type anomalous photo-thermoelectric (photo-TE) effect was confirmed for Pt/WO3 and Pt/HyWO3−x. HyWO3−x is a protonated WO3 after the gaschromic (GC) reaction of WO3 in Pt/WO3. The anomalous photo-TE effect was that both the electrical conductivity (σphoto) and the absolute value of the Seebeck coefficient (Sphoto) increased under UV light or visible light irradiation. After stopping the irradiation, σphoto and Sphoto decreased. In contrast, an n-type normal photo-TE effect was observed for PtOx/HyWO3−x after the GC reaction of PtOx/WO3, in which σphoto increased and the absolute value of Sphoto decreased under ultraviolet (UV) light irradiation, and vice versa after stopping the irradiation. These findings indicate that Pt was responsible for the anomalous photo-TE effect due to the electron accumulation capability of Pt, to which electrons were transferred from the conduction band of HyWO3−x. In contrast, electrons could not energetically transfer from HyWO3−x to PtO2, which existed in PtOx particles at the surface. Therefore, PtOx/HyWO3−x behaved similar to sole HyWO3−x, indicating the normal photo-TE effect. [ABSTRACT FROM AUTHOR]

Magnons are quasiparticles of spin waves, carrying both thermal energy and spin information. Controlling magnon transport processes is critical for developing innovative magnonic devices used in data processing and thermal management applications in microelectronics. The spin ladder compound S r 14 C u 24 O 41 with large magnon thermal conductivity offers a valuable platform for investigating magnon transport. However, there are limited studies on enhancing its magnon thermal conductivity. Herein, we report the modification of magnon thermal transport through partial substitution of strontium with yttrium (Y) in both polycrystalline and single crystalline S r 14 − x Y x C u 24 O 41. At room temperature, the lightly Y-doped polycrystalline sample exhibits 430% enhancement in thermal conductivity compared to the undoped sample. This large enhancement can be attributed to reduced magnon-hole scattering, as confirmed by the Seebeck coefficient measurement. Further increasing the doping level results in negligible change and eventually suppression of magnon thermal transport due to increased magnon-defect and magnon-hole scattering. By minimizing defect and boundary scattering, the single crystal sample with x = 2 demonstrates a further enhanced room-temperature magnon thermal conductivity of 19 W m − 1 K − 1 , which is more than ten times larger than that of the undoped polycrystalline material. This study reveals the interplay between magnon-hole scattering and magnon-defect scattering in modifying magnon thermal transport, providing valuable insights into the control of magnon transport properties in magnetic materials. [ABSTRACT FROM AUTHOR]

2D Janus Rashba semiconductors, which break both the mirror symmetry in the crystal structure and the spin degeneracy in the energy band, provide a promising platform to optimize thermoelectric performance. Herein, we use first-principles and Boltzmann transport theory to investigate the electron and phonon transport properties for Janus semiconductors of monolayer Si2AsSb and Si2SbBi. The strong Rashba spin-splitting is found in both Janus monolayers especially for Si2SbBi, which decreases the bandgaps and makes the valence bands more dispersive, resulting in decreased p-type Seebeck coefficient and increased p-type electrical conductivity. The lattice thermal conductivities of both monolayers are not low due to the weak phonon anharmonicity, strong chemical bonding, and long phonon relaxation time. The low lattice thermal conductivity of Si2SbBi than Si2AsSb mainly originates from the low phonon group velocity. Both monolayers exhibit better thermoelectric performance in n-type than in p-type. The competition among Seebeck coefficient, electrical conductivity, and electronic thermal conductivity makes the difference of optimal thermoelectric figure of merits in n-type without and with Rashba spin–orbit coupling slight for Si2AsSb, but it is significant for Si2SbBi. Within Rashba spin–orbit coupling, the optimal figure of merits at 700 K reach 0.65 and 0.59 for Si2AsSb and Si2SbBi, respectively, which indicate the potential thermoelectric applications, and will stimulate the broad study on thermoelectric properties of 2D Janus Rashba semiconductors. [ABSTRACT FROM AUTHOR]

Magnons are quasiparticles of spin waves, carrying both thermal energy and spin information. Controlling magnon transport processes is critical for developing innovative magnonic devices used in data processing and thermal management applications in microelectronics. The spin ladder compound S r 14 C u 24 O 41 with large magnon thermal conductivity offers a valuable platform for investigating magnon transport. However, there are limited studies on enhancing its magnon thermal conductivity. Herein, we report the modification of magnon thermal transport through partial substitution of strontium with yttrium (Y) in both polycrystalline and single crystalline S r 14 − x Y x C u 24 O 41. At room temperature, the lightly Y-doped polycrystalline sample exhibits 430% enhancement in thermal conductivity compared to the undoped sample. This large enhancement can be attributed to reduced magnon-hole scattering, as confirmed by the Seebeck coefficient measurement. Further increasing the doping level results in negligible change and eventually suppression of magnon thermal transport due to increased magnon-defect and magnon-hole scattering. By minimizing defect and boundary scattering, the single crystal sample with x = 2 demonstrates a further enhanced room-temperature magnon thermal conductivity of 19 W m − 1 K − 1 , which is more than ten times larger than that of the undoped polycrystalline material. This study reveals the interplay between magnon-hole scattering and magnon-defect scattering in modifying magnon thermal transport, providing valuable insights into the control of magnon transport properties in magnetic materials. [ABSTRACT FROM AUTHOR]

This work presents the excess noise and thermoelectric (Seebeck) measurements on polycrystalline vanadium dioxide (VO2) thin films. Noise spectral power density (SPD) of current fluctuations in the semiconducting (SC) phase had a typical flicker noise (f−γ) characteristic with an average slope parameter γ of 1.13. Normalized SPD (Sn) values obtained in the SC-phase indicate that the noise originates in the bulk of the film. On the contrary, in the metallic (M)-phase, γ values were greater than unity, and the observed Sn values indicated that the origin of the noise is most likely from the contacts or surface rather than the bulk. A general decrease was observed in Sn by a factor of 4–5 from the SC- to M-phase. Moreover, Sn in the SC-phase showed no temperature dependence. An interpretation based on the number of charge carrier fluctuations in Hooge's model led to an unrealistically high Hooge parameter and had to be ruled out. We propose that the fluctuations are related to the mobility fluctuations of carriers arising primarily from grain-boundary scattering which explains the observed characteristics well. The Seebeck coefficients (S) obtained under both heating and cooling schedules showed the n-type nature of magnetron-sputtered VO2 films in the SC-phase. Differently, in the M-phase, the S value was positive. The S values obtained from the cooling schedule signified the low percolation threshold of the metal-to-insulator transition already demonstrated for VO2 thin films grown on r-cut sapphire using the Efros–Shklovskii percolation model. [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]

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 this study, we systematically investigated the anomalous Nernst effect in perpendicularly magnetized amorphous TbFeCo thin films with various compositions. It was found that the magnitude of the off diagonal thermopower (ODT), which corresponds to the anomalous Nernst effect, can be uniformly explained with respect to the Tb content regardless of the concentration above or below the compensation composition. The maximum ODT of 1.3 μ V/K and the thermoelectric conductivity of 1.59 A/mK at room temperature were obtained, which is more significant than other perpendicular magnetic anisotropy thin films to achieve a large Nernst voltage for roll-type thermoelectric devices. By considering the thermoelectric tensor, Mott's equation, and the scaling law, it was shown both experimentally and theoretically that the magnitudes of the first and second terms contributing to the anomalous Nernst effect are comparable. It was also found that the ODT of TbFeCo thin films is twice or more significant than the product of the Seebeck coefficient and the Hall angle. Furthermore, amorphous metals and Mn-alloys with a large Berry curvature are located above the relation that the ODT is twice the product of the Seebeck coefficient and the Hall angle, which means that amorphous metals are expected to enhance the ANE. [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]

We present an atomistic simulation of thermoelectric properties in cove-edged graphene nanoribbons (CGNRs) via the nonequilibrium Green's function. Different from gapless zigzag graphene nanoribbons (ZGNRs), CGNRs exhibit a noticeable bandgap. Such a bandgap can be modulated by varying three structural parameters (namely, the width N, the distance between adjacent coves m, as well as the shortest offset n) of CGNRs, which can give rise to the transition from semiconducting to semi-metallic. Due to the less dispersive phonon bands and the decrease in the number of phonon channels of CGNRs, they are found to have the lower phonon thermal conductance than ZGNRs. Modulation of CGNRs can produce over tenfold improvement of the maximum of ZT compared to ZGNRs. This improvement is due to the promotion of the Seebeck coefficient together with the degradation of the phonon thermal conductance of CGNRs compared to ZGNRs. [ABSTRACT FROM AUTHOR]

The development of Ga-doped Zinc Oxide (GZO) films from nontoxic, abundant elements using a cost-effective and scalable approach is crucial for the profitability and sustainability of thermoelectric applications. Challenges in formulating GZO film inks have led to extensive experimentation to enhance their thermal, structural, mechanical, and room-temperature thermoelectric properties by adjusting ink concentration and annealing treatment. Increasing the GZO nanoparticle concentration reduced the melting temperature and crystallinity, whereas annealing at 200 °C decomposed the polyethylene oxide (PEO) binder. TEM analysis revealed the polycrystalline structure of the GZO nanoparticles and their interaction with the binder, while XRD patterns confirmed the characteristic peaks of the GZO films; annealing effectively eliminated the PEO diffraction peaks. The GZO films from the concentrated 1.24M ink exhibited minimal grain growth, reduced lattice strains, uniform elemental distribution, and enhanced surface texture and conductivity, which were further improved by annealing. Increasing the GZO nanoparticle concentration facilitated the formation of a conductive network, while annealing enhanced the conductivity by promoting the formation of a cohesive, interconnected network through impurity removal, nanoparticle redistribution, and coalescence. Consequently, the annealed 1.24M film demonstrated the highest nanohardness of 791 MPa and a thermoelectric power factor of 1.78 nW/m∙K2 at room temperature, which were attributed to enhanced electrical conductivity and Seebeck coefficient through concentration and annealing synergies. [ABSTRACT FROM AUTHOR]

Heat is produced by all machinery, including microprocessors and jet engines, as well as by industrial processes that produce goods from steel to food. There is still a strong desire for alternative energy sources in this day of ecologically conscious and sustainable energy needs. The recovery of heat from waste heat into beneficial electrical energy provides a simple energy source with enormous potential. Thermoelectrics is one of the popular technologies, which can convert heat into electricity, making them useful for power generation. Tin telluride (SnTe), a significant type of newly developed thermoelectric material, has drawn a lot of attention due to its low toxicity and environmentally friendly characteristics. Here, we synthesize Bi/Se co-doped SnTe (Sn 1-x Bi x Te 0.97 Se 0.03 (x = 0, 0.02, 0.04, 0.06)) samples by employing the solid-state metathesis route. The results of this work suggest that the combined action of cationic and anionic substitution of Bi and Se to SnTe matrix could potentially modify the microstructure and band structure of SnTe, thereby effectively improving its electronic, mechanical, and thermal transport properties. In line with the experimental findings, the samples show degenerate semiconducting electronic transport behaviour throughout the temperature range. The maximum Seebeck coefficient is found to be ∼84 μV/K and the total thermal conductivity is reduced to 1.6 W/mK at 573 K in a 6 % Bi-doped sample, which is 2.2 times less than the pristine sample. The Sn 0.94 Bi 0.06 Te 0.97 Se 0.03 sample has a maximum ZT of approximately 0.23 at 573 K, which is three times higher than the pristine sample because of the combined regulation of cation-anion co-doping and an elevated power factor of 936 μW/K2m in Sn 0.96 Bi 0.04 Te 0.97 Se 0.03 sample at 573 K, which is 1.82 times higher than that of pristine SnTe. Considering these findings, it appears that Bi-Se co-doped SnTe is a promising material for thermoelectric applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a series of S 0. 0 5 Co4Sb 1 1. 6 Te 0. 4 samples were prepared by high pressure and high temperature (HPHT) method under different pressures. The synthesis time was shortened from several days to 0.5 h. Te doping and S filling simultaneously optimized the thermal and electrical transport properties of the CoSb3 materials. We found a porous architecture containing rich grain boundaries, different grain sizes, nano- to micrometer-sized pores, and a large number of dislocations, which can scatter a wide spectrum of phonons. Seebeck coefficient α , electrical resistivity ρ , and thermal conductivity κ were measured between 295 K and 773 K. The minimum thermal conductivity of S 0. 0 5 Co4Sb 1 1. 6 Te 0. 4 synthesized at 3.0 GPa was 1.23 Wm − 1  K − 1 , and its maximum zT value reached 1.07 at 773 K, especially the lattice thermal conductivity was as low as 0.49 Wm − 1  K − 1 . [ABSTRACT FROM AUTHOR]

We herein introduce a microwave-assisted solid state technique to synthesize zintl compounds YbCd 2-x Zn x Sb 2 (0.0 ≤ x ≤ 2.0) in short time of 10 min by utilizing an active carbon as a susceptor material. Here, we report an energy-saving preparation route using a domestic microwave oven. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz ampoule resulting in near single phase compounds. By studying the crystal structure using X-Ray diffraction (XRD) and SEM-EDS, the hexagonal crystal structures of the prepared samples were identified. Thermoelectric characterizations have been performed for all obtained samples and among them the compound YbCd 1. 6 Zn 0.4 Sb 2 is found as the best one because it has Seebeck coefficient of −22.68 μV/k, and power factor of 8.20 μWcm−1k−2 at 523 K with carrier concentration of 3.04 × 1021 cm−3 at 300 K. [ABSTRACT FROM AUTHOR]

The Bi 2 Sr 2 Co 2 O y ceramic, known for its stability as a p-type thermoelectric material, has limited thermoelectric performance that necessitates enhancement. In this study, Bi 2- x Cu x Sr 2 Co 2 O y (x = 0, 0.025, 0.05, 0.1, 0.2) ceramic samples were synthesized using the conventional solid-state reaction method. Substitution of Cu2+ for Bi3+ in the samples increased carrier concentration, significantly reducing electrical resistivity. Utilizing the single parabolic band (SPB) model, it was determined that Cu incorporation led to an increased effective mass, thereby enhancing the Seebeck coefficient. Additionally, fine grains and lattice defects induced by Cu2+ substitution effectively scattered phonons, resulting in an ultra-low thermal conductivity of 0.59 Wm−1K−1 at 923 K for the Bi 1.8 Cu 0.2 Sr 2 Co 2 O y sample. Consequently, Cu substitution optimized both the electrical and thermal transport properties of Bi 2-x Cu x Sr 2 Co 2 O y samples. The dimensionless thermoelectric figure of merit (ZT) for Bi 1.95 Cu 0.05 Sr 2 Co 2 O y reached 0.31 at 923 K, representing a 63 % increase over the pristine Bi 2 Sr 2 Co 2 O y sample. [ABSTRACT FROM AUTHOR]

Since SrTiO 3 is attractive due to its versatile electronic properties ranging from dielectric to semiconducting behavior, the effect of systematic co-substitution of various A-site cations on the electronic structure and transport properties of oxygen-deficient SrTiO 3- δ bulk ceramics was analyzed. The materials were synthesized by reverse co-precipitation method and densified by spark plasma sintering (SPS) in a vacuum, followed by a post-thermal treatment in a reducing atmosphere (5 % H 2 /Ar). The phase purity was confirmed by X-ray diffraction (XRD), different microstructures were revealed by scanning electron microscopy (SEM), and characterization in terms of electrical conductivity (σ el) and Seebeck coefficient (S) were performed. The largest power factor was obtained with Sr 0.25 Ca 0.25 Na 0.25 La 0.25 TiO 3-δ by maintaining electrical conductivity while increasing the Seebeck coefficient. Density Functional Theory (DFT) calculations were applied to obtain information on band structures, the projected density of states (PDOS), and electron density differences (EDD). Band structures indicated that oxygen deficiency essentially changed the conductive nature of the studied materials by shifting the Fermi level to the conductive zone, while PDOS plots define the role of each element located at the A site. The electronic structure is affected to the greatest extent in the cases when Nd and Pr are present at the A-site. However, the obtained experimental and computational (DFT) results could not completely match and explain all phenomena since understanding the effect of different cations at A-site on oxygen vacancy formation seems to be a challenging task, and therefore, some hypotheses are proposed. This work attempts to understand the role of a particular cation at A-site on the electronic band structure and its relevance to the formation of oxygen vacancies, thereby providing valuable insights for future high-entropy perovskite titanates with improved transport properties. [ABSTRACT FROM AUTHOR]

Thermally chargeable supercapacitors can collect low‐grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics. However, the low Seebeck coefficient and heat‐to‐electricity conversion efficiency hinder further application. In this paper, we designed a high‐performance thermally chargeable supercapacitor device composed of ZnMn2O4@Ti3C2Tx MXene composites (ZMO@Ti3C2Tx MXene) electrode and UIO‐66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro‐propylene ionogel electrolyte, which realized the thermoelectric conversion and electrical energy storage at the same time. This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K−1, thermal voltage of 243 mV, and outstanding heat‐to‐electricity conversion efficiency of up to 6.48% at the temperature difference of 4.4 K. In addition, this device showed excellent charge–discharge cycling stability at high‐temperature differences (3 K) and low‐temperature differences (1 K), respectively. Connecting two thermally chargeable supercapacitor units in series, the generated output voltage of 500 mV further confirmed the stability of devices. When a single device was worn on the arm, a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics. [ABSTRACT FROM AUTHOR]

The structure–property relationship at interfaces is difficult to probe for thermoelectric materials with a complex interfacial microstructure. Designing thermoelectric materials with a simple, structurally‐uniform interface provides a facile way to understand how these interfaces influence the transport properties. Here, we synthesized Bi2−xSbxTe3 (x = 0, 0.1, 0.2, 0.4) nanoflakes using a hydrothermal method, and prepared Bi2−xSbxTe3 thin films with predominantly (0001) interfaces by stacking the nanoflakes through spin coating. The influence of the annealing temperature and Sb content on the (0001) interface structure was systematically investigated at atomic scale using aberration‐corrected scanning transmission electron microscopy. Annealing and Sb doping facilitate atom diffusion and migration between adjacent nanoflakes along the (0001) interface. As such it enhances interfacial connectivity and improves the electrical transport properties. Interfac reactions create new interfaces that increase the scattering and the Seebeck coefficient. Due to the simultaneous optimization of electrical conductivity and Seebeck coefficient, the maximum power factor of the Bi1.8Sb0.2Te3 nanoflake films reaches 1.72 mW m−1 K−2, which is 43% higher than that of a pure Bi2Te3 thin film. [ABSTRACT FROM AUTHOR]

The emergence of new functionalities in transition metal oxides and their interfaces poses an important challenge. Many recent discoveries regarding the polar/nonpolar interface between perovskite oxides open new avenues for modern applications. SrTiO3/LaCrO3 heterostructures are particularly intriguing due to a polar discontinuity along the [001] direction, giving rise to two distinct and controllable interface structures, TiO2-LaO and SrO-CrO2, which exhibit new and promising electronic and thermoelectric transport properties. Through a combination of first-principles simulations based on density functional theory and the Boltzmann transport equation, we have calculate and discuss the structural, electronic, valence band offset, and thermoelectric properties of SrTiO3, LaCrO3, and SrTiO3/LaCrO3 heterostructures. The temperature dependence of the Seebeck coefficient, electrical conductivity, electronic thermal conductivity, and figure of merit is determined. Furthermore, we highlight the effect of the interface between the polar perovskite LaCrO3 and the nonpolar SrTiO3(001) on the thermoelectric properties, wherein we observed a change in the metal–semiconductor transport behavior. These results constitute an important advancement in our understanding of the thermoelectric properties at polar/nonpolar perovskite oxide interfaces. [ABSTRACT FROM AUTHOR]

Copper selenide (Cu2Se) has attracted extensive research interest in the field of thermoelectricity due to its large abundance of constituent elements, environmental friendliness, and excellent thermoelectric properties. In this study, a facile and low-cost hydrothermal synthesis method combined with vacuum sintering was used for Cu2Se-based sample preparation, and the possibility of improving the thermoelectric properties of Cu2Se by doping with rare earth elements (Tm, Er, Lu) was explored using experimental tests and density functional theory calculations. The electronic structure calculations show that the electrical conductivity is increased due to the increased electron density after rare earth element doping. At the same time, the sharp increase in the density of states at the Fermi level after rare earth element doping enhances the Seebeck coefficient of the Cu2Se matrix. The experimental results show that the thermoelectric properties of all the samples doped with rare earth elements (Tm, Er, Lu) were improved compared to the Cu2Se matrix. The doping of rare earth elements led to an increase in point defects and the formation of pores in the samples, which play an important role in reducing the thermal conductivity. Among them, the Tm-doped Cu1.995Tm0.005Se sample reached a maximum ZT value of 0.80 at 773 K, which is a nearly 43% increase compared to the Cu2Se matrix (ZTmax = 0.56). [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) GeTe is a popular medium-temperature thermoelectric material, but few studies have focused on strategies for improving its thermoelectric performance. To further investigate the thermoelectric properties of two-dimensional GeTe, different atomic defects are introduced, and the electronic structure and thermoelectric properties are systematically investigated via first-principles calculations and the semiclassical Boltzmann theory. Compared with that of three-dimensional (3D) GeTe, the Seebeck coefficient of 2D GeTe increases from 144 μV K−1 to 560 μV K−1 at 700 K, and the thermal conductivity decreases from 3.3 W m−1 K−1 to 2.3 W m−1 K−1. Thus, the ZT value increases from 0.8 to 1.14. On the basis of these results, the influence of vacancy atomic defects on the thermoelectric performance is investigated. With single-atom defects (SV-Ge and SV-Te), the ZT value increases at constant temperature. However, for double-atom defects in monolayer GeTe, the ZT value increases when DV-585 defects are present but decreases to varying degrees when DV-Ge and DV-Te defects are present. The ZT value of monolayer GeTe with DV-585 defects has an average increase of 0.56 at 300–800 K, which accords well with the experimental results. This study indicates that introducing single-atom vacancy defects somewhat improves the thermoelectric performance of monolayer GeTe, which provides an important point of reference for the development of GeTe in the two-dimensional materials field. [ABSTRACT FROM AUTHOR]

Tin sulfide (SnS) is widely recognized as a promising material for thermoelectrics owing to its layered structure, anharmonicity, earth abundance, and minimal toxicity. This study focuses on controlling the hole concentration of SnS by substituting isovalent Zn through a vacuum melting technique. The presence of point defects, such as mass fluctuations and strain field fluctuations, along with lattice dislocations and stacking faults, results in a drop in thermal conductivity. The mass difference between Zn dopant and Sn host atoms plays a significant role in point defect scattering when Zn is substituted in the SnS lattice. Additionally, variations in size and interatomic coupling forces between Zn and Sn atoms contribute to the amplification of point defect scattering, effectively reducing the lattice thermal conductivity. Furthermore, the diminished lattice thermal conductivity of SnS samples with Zn substitution is ascribed to the decreased phonon mean free path. The synergy of multi-scale scattering results in a low thermal conductivity of 0.88 W m−1 K−1 at 773 K. Further, Zn substitution slightly improved the carrier concentration from 6.88 × 1015 cm−3 to 2.31 × 1016 cm−3 resulting in enhanced electrical conductivity without the drastic decrement in the Seebeck coefficient. This in turn significantly improved the power factor to 42.6 μW m−1 K−2 for the Sn0.95Zn0.05S sample. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials are significant for sustainable development because they can be used to harvest waste heat into electricity. Organic TE materials have unique merits including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. But their TE properties particularly the Seebeck coefficient are notably lower than the inorganic counterparts. Here, a poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) film is reported with a very high Seebeck coefficient and figure of merit (zT) at room temperature through secondary doping, dedoping engineering, and ionic energy filtering. The PEDOT:PSS films are successively treated with acid, base, and vitamin C that is a reductant, and then coated with 1‐ethyl‐3‐methylimidazolium dicyanamide (EMIM:DCA) that is an ionic liquid. This can exhibit a record‐high Seebeck coefficient and power factor of 111 µV K−1 and 1285 µW m−1 K−2, respectively, and the corresponding zT value is 1.05. This is the highest zT value for polymers and polymer composites, and it is comparable to that of the best inorganic TE materials. [ABSTRACT FROM AUTHOR]

Higher Manganese Silicides (HMS) are the best p-type materials beneficial for intermediate-temperature range thermoelectric device applications due to their high thermal stability and inexpensive constituent elements. Although the cost-effective HMS materials possess high thermal stability, they are concerned with high thermal conductivity values. The nanocomposite approach was promised to lower the thermal transport properties without affecting the electrical transport properties, which is experimented in the present work. The higher manganese silicide with varying weight percentages of nano-structured Si 0.8 Ge 0.2 B 0.02 inclusions was experimented to decrease the thermal conductivity and to enhance the electrical properties. The lowest thermal conductivity value of ≃ 2.24 W/mK was reported with 2 wt% Si 0.8 Ge 0.2 B 0.02 addition in HMS material. Also, the HMS-2 wt. % Si 0.8 Ge 0.2 B 0.02 improved the transport properties, electrical conductivity and Seebeck coefficient values of ≃ 4 × 104 S/m and ≃ 220 μV/K respectively. Furthermore, various mathematical models were proposed here to simulate the composite approach results, which were then correlated with experimental results. [ABSTRACT FROM AUTHOR]

Misfit‐layered calcium cobaltite [Ca2CoO3‐δ]0.62[CoO2] is an outstanding p‐type semiconducting thermoelectric with strong anisotropic properties. Texture engineering is crucial for enhancing its thermoelectric performance in polycrystalline ceramics. The in‐plane orientation of the grains improves the Seebeck coefficient and electrical conductivity, while the multi‐scale parallel interfaces scatter phonons and reduce thermal conductivity. Here, a tandem process of spark plasma sintering and edge‐free spark plasma texturing is used to produce dense and highly textured calcium cobaltite ceramics. The resulting ceramic shows a high degree of texturization, secondary phases, and enhanced electrical conductivity of 246 S cm−1 together with a strongly improved Seebeck coefficient of 224 µV K−1 at 1073 K. High grain ordering leads to carrier mobility of 0.49 cm2 V−1 s−1, which has a positive effect on both parameters. With a power factor of 12.4 µW cm−1 K−2 at 1073 K in air, previous thermoelectric performances of calcium cobaltite are surpassed, regardless of its form: pristine, doped, or composite. By combining the high power factor with a relatively low thermal conductivity, a remarkable figure‐of‐merit of 0.49 at 1073 K in air is obtained for the textured polycrystalline ceramic, which reaches 60 % of the figure‐of‐merit of a calcium cobaltite single crystal. [ABSTRACT FROM AUTHOR]

High‐performance polycrystalline calcium cobaltite ceramic was synthesized via electrospinning of nanoribbons, followed by dual‐process compaction using spark plasma sintering and edge‐free spark plasma texturing. The combination of nanoribbon electrospinning and this multistage sintering technique was employed for the first time and resulted in exceptionally well‐textured thermoelectric ceramics. The textured ceramic had excellent thermoelectric properties. At 1073 K, the ceramic exhibited an electrical conductivity of 268 S cm−1, a Seebeck coefficient of 247 µV K−1 and a heat conductivity of 3.3 W m−1 K−1. In addition, the power factor and figure‐of‐merit reached enormously high values of 16.3 µW cm−1 K−2 and 0.53, respectively. This represents the highest thermoelectric performance reported to date not only for electrospun, polycrystalline calcium cobaltite fiber ceramics, but also for undoped polycrystalline calcium cobaltite ceramics. [ABSTRACT FROM AUTHOR]

Quasi‐solid‐state thermocells (QTECs) show promise as a power source for wearable devices by converting body heat into electricity. While significant progress has been made with p‐type elements for QTECs, challenges remain with their n‐type counterparts. Here, a high‐performance n‐type QTEC element is presented, using a copolymer hydrogel that outperforms conventional p‐type elements. This copolymer hydrogel combines hydrophilic zwitterionic sulfobetaine methacrylate (SBMA) for ionic conduction and hydrophobic methyl methacrylate (MMA) for structural stability. By increasing the MMA content from 35 to 100 wt.%, versatile control is achieved over the hydrogel's elastic modulus (72 kPa to 127.7 MPa) and tensile strength (54 kPa to 6.7 MPa). A high mechanical toughness of 7.2 MJ m−3 is also achieved at 68 wt.% MMA. The mechanically robust and high toughness p(SBMA‐MMA) hydrogel is then immersed in Fe(ClO4)2/3 solutions of different concentrations to evaluate its performance as an n‐type QTEC element. The hydrogel with 0.8 M Fe(ClO4)2/3 exhibits a high ionic Seebeck coefficient of −1.7 mV K−1, a power density of 1.1 mW m−2 K−2, and an elastic modulus of 1.6 MPa, which is similar to that of human skin. Finally, the optimized n‐type p(SBMA‐MMA) hydrogels demonstrate the potential application for wearable devices. [ABSTRACT FROM AUTHOR]

Since crystal structure dictates the resultant physical properties of materials, titled physical features of the P21 monoclinic SiGe semiconductors, which are still unclear, have been revealed by density functional theory (DFT). The electronic band gap value with 0.49 eV was found to be in the order of previously published cubic and hexagonal closed-packed SiGe semiconductors. Surprisingly, P21 monoclinic SiGe has a room temperature Seebeck coefficient of 1500 μ V/K which is higher than the reported data of both cubic and hexagonal SiGe alloys. Further, the mechanically stable P21 monoclinic phase of the SiGe displays a brittle mechanical character with clear elastic anisotropy has also been deduced. The P21 monoclinic phase of the SiGe can be also considered a good high-dielectric material and beneficial for practical applications of IR or UV goals due to its high refractive index. [ABSTRACT FROM AUTHOR]

Due to their distinct characteristics and prospective uses in several disciplines, half-Heusler (HH) materials are a family of intermetallic compounds that have garnered a lot of attention. HH compounds have a cubic crystal structure and exhibit a wide range of electronic, optical, mechanical and thermoelectric characteristics. Direct bandgap acquired by the WC-GGA (TB + mBJ) approach is 1.07 eV (2.26 eV), 0.61 eV (1.71 eV), 0.76 eV (1.68 eV), and 0 eV (0.78 eV) for KMgP, KMgAs, KMgSb, and KMgBi, respectively. Threshold power ε 2 (ω) of KMgX (X = P , As, Sb, and Bi), starts from 2.218, 1.701, 1.674, and 0.776 eV, so they exhibit the distinct peaks at 4.014, 3.742, 3.388, and 3.197 eV, correspondingly. Among these materials, the maximum value of Seebeck coefficient (S) has been attained at 300 K. Specifically, KMgP achieves the highest value of S at 3.134 mV/K, followed by KMgAs at 2.947 mV/K, KMgSb at 2.893 mV/K, and KMgBi at 1.431 mV/K, all in their respective p-type configurations. In order to determine the compound's stability, we will explore the elastic and thermodynamic properties. We will also discuss their possible applications in photovoltaic and thermoelectric devices. [ABSTRACT FROM AUTHOR]

First-principles simulations are conducted to explore the structural stability, electronic properties, and optical responses of pristine and boron- or nitrogen-doped monolayers graphene. The computed electronic density of states revealed that the substitutional doping of boron impurity atoms on monolayer graphene (MLG) shifts the Dirac point upward, although the substitution of nitrogen impurity atoms in graphene pushes the Dirac point downward the Fermi level. This could exhibit that upon the doping of MLG with boron or nitrogen, respectively, p-type or n-type semimetal is acquired. The overall optical spectral properties of the substituted graphene with boron or nitrogen atoms are simulated and compared with the optical spectra results of pure graphene. The optical features of pristine and doped MLG are determined by taking the interband and intra-band transitions into account ranging from the far-infrared to the ultraviolet regime of the electromagnetic radiation. A remarkable red shift in the optical spectra of the doped MLG towards the visible regime of radiation is established. An enhanced reflectivity illustrated that concentration-dependent optical properties of boron and nitrogen-doped MLG happen at lower electromagnetic radiation regimes. In addition, we explored the thermoelectric behaviors of the pristine/doped graphene monolayers with 4 × 4 supercells. We found a significant improvement in the electrical conductivity of graphene when doped with boron or nitrogen impurities. However, an increase in the electrical conductivity has textured a decrease in the Seebeck coefficients. Improvement in the electrical conductivity is attributed to an interesting effect on the graphene monolayers' power factor (PF). These findings indicate a positive impact of the dopants on the thermoelectric properties of graphene monolayers and reveal that they are potential materials for thermoelectric applications and nanodevices. [ABSTRACT FROM AUTHOR]

A novel transparent photothermoelectric device has been developed, leveraging the advantageous thermoelectric properties of transparent conductive oxide thin films such as aluminium‐doped zinc oxide (AZO), and the absorption or reflectance properties of indium thin oxide (ITO) for near‐infrared (NIR) radiation. AZO exhibits transmittance exceeding 70% across a broad range of wavelengths (400–2200 nm) and a high Seebeck coefficient (120–150 µV K−1). Through heat treatments between 300 and 500 °C, ITO's NIR absorption is optimized to values above 40% in the 1–1.5 µm range. The optimized thickness of the ITO/Ag/ITO multilayer structure has an 80% reflectance for wavelengths above 1.2 µm. Integrating these two layers on a transparent thermoelectric AZO film creates a thermal gradient induced by infrared (IR) radiation. This gradient results in a photothermal potential that is sensitive to sunlight intensity, with a sensitivity measured at 1.5 mV W−1. This innovation marks a significant advancement in technology, showcasing the potential for transparent devices in smart windows. [ABSTRACT FROM AUTHOR]

Herein, the impact of exposing the perovskite compound Pr0.5Sr0.5MnO3 to oxygen plasma is explored by comparing the structural and transport properties of the exposed samples to those of the unexposed ones. The Pr is oxidized to PrO2 in the investigated samples due to plasma exposure. The alterations in the transport properties can be linked to the changes in MnOMn bond angle and MnO bond length due to plasma exposure, as indicated by X‐ray diffraction analysis. Additionally, exposure to oxygen plasma increases the conductivity by incorporating oxygen into the exposed samples, making them oxygen‐rich. Detailed analysis of the resistivity and thermoelectric power data indicates that small polarons are responsible for conduction at high temperatures, while at low temperatures, variable range polarons take over. The negative value of the thermopower at all temperatures proclaims that the electrons behave as the dominant charge carriers. [ABSTRACT FROM AUTHOR]

This study introduces the synthesis of a hybrid thermoelectric material with enhanced conductivity and a high Seebeck coefficient, leveraging the properties of Te nanowires (NWs) and the conductive polymer PEDOT:PSS. Te NWs were synthesized using the galvanic displacement reaction. To further enhance conductivity, Ag-Te NWs were synthesized under optimized conditions via the Ag topotactic reaction, achieving desired results within 7 min using ethylene glycol and AgNO3. This hybrid material exhibited an electrical conductivity of 463 S/cm, a Seebeck coefficient of 69.5 μV/K at 300 K, and a power factor of 260 μW/mK2. These metrics surpassed those of conventional Te/PEDOT:PSS hybrids by a factor of 3.6, highlighting the superior performance of our approach. This study represents a significant advancement in thermoelectric materials, improving both conductivity and efficiency. [ABSTRACT FROM AUTHOR]

Thermoelectric textile devices represent an intriguing avenue for powering wearable electronics. The lack of air‐stable n‐type polymers has, until now, prevented the development of n‐type multifilament yarns, which are needed for textile manufacturing. Here, the thermomechanical properties of the recently reported n‐type polymer poly(benzodifurandione) (PBFDO) are explored and its suitability as a yarn coating material is assessed. The outstanding robustness of the polymer facilitates the coating of silk yarn that, as a result, displays an effective bulk conductivity of 13 S cm−1, with a projected half‐life of 3.2 ± 0.7 years at ambient conditions. Moreover, the n‐type PBFDO coated silk yarn with a Young's modulus of E = 0.6 GPa and a strain at break of εbreak = 14% can be machine washed, with only a threefold decrease in conductivity after seven washing cycles. PBFDO and poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated silk yarns are used to fabricate two out‐of‐plane thermoelectric textile devices: a thermoelectric button and a larger thermopile with 16 legs. Excellent air stability is paired with an open‐circuit voltage of 17 mV and a maximum output power of 0.67 µW for a temperature difference of 70 K. Evidently, PBFDO coated multifilament silk yarn is a promising component for the realization of air stable thermoelectric textile devices. [ABSTRACT FROM AUTHOR]

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

The synthesis of transparent thermoelectric materials, particularly at low processing temperature possesses a good promise for future power generation by renovating waste heat into electrical energy. The fabrication of invisible thermoelectric module is hindered by limited choices of appropriate p-type transparent thermoelectric materials so far. The present study deals with the growth and characterization of optically transparent p-type copper iodide (γ-CuI) thin films. Thermal annealing (maximum up to 200 °C) was performed to tune the electrical and optoelectronic properties for nurturing the thermoelectric performance. Annealing induced microstructural modifications instigated the preferential crystal growth by regulating the surface morphology. Low thermal conductivity is credited to strong phonon scattering leading to improved thermoelectric performance. Consequently, we attain a record Seebeck coefficient of ∼270 μV/K and power factor of ∼20 μW/(m·K2) that is almost two-order of magnitude higher as compared to conventional p-type transparent TE materials, indicating the potential of transparent γ-CuI thin films regarding its practical applicability in transparent thermoelectric devices. [ABSTRACT FROM AUTHOR]

Mg-doped Al 2 O 3 protective layers were deposited on Pt–PtRh 10 (S-type) thin film thermocouples (TFTCs) by reactive magnetron sputtering. The changes in the composition, microstructure, and element distribution of the Mg-doped Al 2 O 3 films before and after annealing at 1200 °C for 3 h were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The results indicate that incorporating MgO into Al 2 O 3 as an enhancement phase not only inhibits the crystallization and phase transformation of Al 2 O 3 but also promotes the formation of MgAl 2 O 4 , sequentially further enhancing the material's high-temperature protective properties. The thermoelectric properties of S-type TFTCs with 1.6 μm thick Al 2 O 3 and Mg-doped Al 2 O 3 protective layers were explored, respectively. The results of static calibration at high temperatures demonstrate that the TFTCs with the Mg-doped Al 2 O 3 protective layer can operate at 1148 °C for over 96 h and at 1480 °C for a brief period. Following 4 calibration cycles, compared to the TFTCs with the Al 2 O 3 protective layer, the average Seebeck coefficients of the TFTCs with the Mg-doped Al 2 O 3 protective layer exhibit a slower decline rate, and its drift rate during the 4th cycle is merely 3.28 °C/h. The TFTCs featuring Mg-doped Al 2 O 3 protective layers demonstrate extended lifetimes, superior high-temperature stability, and enhanced reliability when contrasted with those utilizing undoped Al 2 O 3 protective layers. These attributes offer valuable insights into the progression of TFTC technology. [ABSTRACT FROM AUTHOR]

Thin film thermoelectric technology has immense potential to become a next-generation power source for small-scale electronics. However, the rapid development of thin film thermoelectric still lacks a controllable structural design to improve the performance of thermoelectric devices for required temperature applications. This work presented a controlled thermoelectric design of ZnO-based thin films by Al and Mg co-doping using ALD. Herein, the Mg-doped ZnO sample exhibits the highest Seebeck coefficient of −311.83 μVK−1 at 500oC, while the maximum thermoelectric power factor of 3.68 μWcm−1K−2 is obtained at 300oC, which drops for higher temperatures. This decrease in power factor resulted from the reduction in electrical conductivity above 300oC. Similarly, the Al and Mg co-doped ZnO sample (Mg/Al ≈2 at%) exhibits a high thermoelectric power factor of 3.85 μWcm−1K−2 for ZnO based material due to its moderate electrical conductivity and Seebeck coefficient value at 325oC and behave monotonically for elevated temperatures. Scanning electron microscope (SEM) images show the formation of wedge-shaped structures for Al-incorporated samples, which helps to boost the overall thermoelectric performance. Additionally, we performed XRD, UV–Vis, Hall, and AFM analysis to get a deep insight into structural, optical, electrical, and surface features of the grown thin films and their linkage with the thermoelectric properties. [Display omitted] • Growth of Al and Mg co-doped ZnO thin films on quartz substrate using ALD. • SEM measurements reveal the formation of Wedge-shaped morphology for co-doped thin films. • Thermoelectric properties have been improved by tuning the Mg/Al concentration. • The highest thermoelectric power factor of 3.85 μWK−1cm−2 was obtained for the ZMA2 sample at 325oC. [ABSTRACT FROM AUTHOR]

One of the challenges facing our current and future generations is the effective management of energy and its acquisition through more sustainable means. One solution is using materials capable of generating energy from temperature differences. Construction materials could be the answer, as they are already integrated into structures and have good thermoelectric properties. Geopolymers, emerge as a promising candidate due to their enhanced sustainability compared to alternative materials. Our research explored the use of geopolymers for electricity generation from heat. To minimize the usage of kaolin, we incorporated 50 % of two mining residues obtained from old mines located in Portugal. This approach optimizes the utilization of mineral resources and mitigates the environmental impact. Various methods were used to characterize this material, such as X-ray diffraction, simple compressive strength tests and evaluation of thermoelectric properties, such as the Seebeck coefficient and figure of merit. The geopolymers tested exhibit semiconductor characteristics, demonstrating poor heat conduction due to their low thermal conductivity. Regarding thermoelectric properties, these materials display N-type behavior, with a Seebeck Coefficient between −643 μV/°C and −2760 μV/°C. These findings underscore the advantages of utilizing this sustainable material for the widespread implementation of energy management in buildings on a large scale. [ABSTRACT FROM AUTHOR]

This study introduces the synthesis of a hybrid thermoelectric material with enhanced conductivity and a high Seebeck coefficient, leveraging the properties of Te nanowires (NWs) and the conductive polymer PEDOT:PSS. Te NWs were synthesized using the galvanic displacement reaction. To further enhance conductivity, Ag-Te NWs were synthesized under optimized conditions via the Ag topotactic reaction, achieving desired results within 7 min using ethylene glycol and AgNO3. This hybrid material exhibited an electrical conductivity of 463 S/cm, a Seebeck coefficient of 69.5 µV/K at 300 K, and a power factor of 260 µW/Mk². These metrics surpassed those of conventional Te/PEDOT:PSS hybrids by a factor of 3.6, highlighting the superior performance of our approach. This study represents a significant advancement in thermoelectric materials, improving both conductivity and efficiency. [ABSTRACT FROM AUTHOR]

In this study, we thoroughly explored the thermal transport and thermoelectric properties of BN-co-doped phagraphene structures in the context of first-principles computations combined with machine learning interatomic potential (MLIP) techniques. Our results demonstrate that doping positions can critically tune the thermal properties, offering potential advantages for both thermoelectric and heat transfer applications. Notably, enhanced thermal conductivity has been obtained for phagraphene with 10 % co-doping. Additionally, the rectangular structural symmetry of phagraphene plays an important role for targeted thermal transport. Further, we observe negative Grüneisen parameter in these structures, suggesting negative thermal expansion. This will serves as an unique mechanism for controlling the thermal conductivity at different frequencies. Interestingly, n-type behavior of the structures is indicative of its negative Seebeck coefficient within the temperature range of 300–900 K. Moreover, these structures display significantly larger electrical conductivity compared to other two-dimensional (2D) materials. Apart from that, the calculated figure of merit of the structures under a constant relaxation time at 300 K shows considerably better response for some specific doped structures. We believe this study will play an important role in understanding the importance of structural modifications in tailoring the thermal properties of carbon-based 2D systems. [ABSTRACT FROM AUTHOR]

Density functional theory with pesudo potential approximation is used to study XBaB (X = Li , Na, K) half-Heusler compounds structural, magnetic and electrical property using Quantum espresso code and thermoelectric properties were studied using BoltzTrap code. Total energy calculations were carried out in the α , β and γ phases of XBaB compounds in C 1 b type structure. The compounds were stable in α -phase and hence further calculations were focused only on α phase. From the spin polarization calculations, magnetic state was stable than nonmagnetic state and exhibits ferromagnetism at the equilibrium lattice constant with an integer magnetic moment of 2  μ B . From the band structure calculations and through density of states, all the three compounds exhibit half-metallicity with 100% spin polarization by showing semi-conductivity for majority spin and metallicity for minority spin. In addition, thermoelectric properties were investigated for all three compounds. LiBaB is found to have high Seebeck coefficient of 2462 μ VK − 1 and ZT value of 1, compared to other compounds. These materials were found to have high ZT value and hence they can be used for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Kagome metal ScV6Sn6 has been a subject of interest due to the emergence of a first-order structural phase transition with intriguing charge density wave behavior below the transition temperature Tc ∼ 92 K. To explore the thermoelectric properties and provide experimental insights into the nature of the phase transition, we have carried out a combined study by means of the electrical resistivity, Seebeck coefficient, and thermal conductivity measurements on single crystalline ScV6Sn6. Pronounced features near Tc have been characterized by all measured physical quantities. In particular, the Seebeck coefficient exhibits a marked reduction as lowering temperature across Tc, attributed to an imbalance of the contribution from different type of carriers induced by the structural phase transition. From the examination of the electronic and lattice thermal conductivities, we obtained a confirmation that the observed enhancement at Tc is essentially caused by the change of the lattice thermal conductivity, demonstrating the primary importance of lattice distortions for the heat transport of ScV6Sn6. In addition, the lattice thermal conductivity above Tc was found to increase monotonically with temperature. We associated the peculiar phenomenon with lattice fluctuations, highlighting the essence of structural instability in the kagome lattice ScV6Sn6. These results add to the knowledge about the thermal transport properties in kagome materials with a hexagonal HfFe6Ge6-type structure. [ABSTRACT FROM AUTHOR]

Thermoelectric (TE) materials have attracted significant attention because they can be used to directly harvest waste heat into electricity. Organic TE materials like poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have advantages including high mechanical flexibility, low cost, and low intrinsic thermal conductivity. However, their TE properties are notably inferior to their inorganic counterparts. Here, PEDOT:PSS films with very high thermoelectric properties through the sequential treatments with H2SO4, water, and ethanol solution of tetrakis(dimethylamino)ethylene (TDAE) are reported for the first time. The PEDOT:PSS films can exhibit a Seebeck coefficient of 58.2 µV K−1 and electrical conductivity of 1552 S cm−1, and the corresponding power factor is 526 µW m−1 K−2. The water treatment prior to the TDAE solution treatment is crucial for the high TE properties of PEDOT:PSS films. Without the water treatment, the control PEDOT:PSS films exhibit a Seebeck coefficient of only 32.4 µV K−1 and electrical conductivity of 1124 S cm−1, and the corresponding power factor is only 118 µW m−1 K−2. The effect of the water treatment on the Seebeck coefficient is attributed to the swelling of PEDOT:PSS films, which facilitates the penetration of TDAE from solution into the polymer films and thus the reduction of PEDOT:PSS. [ABSTRACT FROM AUTHOR]

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

Utilizing DFT along with Boltzmann transport theory, the structural, elastic, electrical, optical, and thermoelectric properties of half‐Heusler compound RhTiP have been calculated in principle to examine the pressure effect in the range of 0–40 GPa. As pressure increases, the volume and normalized lattice parameter decreased. In addition to satisfying the Born stability criterion, which ensured the compound RhTiP "natural stability," the zero pressure elastic constants and the pressure‐dependent elastic constants are positive up to 40 GPa. The band structure computations guarantee the semiconductor nature of RhTiP, as demonstrated by the presence of electronic band gap of 1.035 eV at zero pressure. Using the Voigt‐Reuss‐Hill (VRH) averaging scheme under pressure, we have determined the values of this compound's bulk modulus B$$ B $$, shear modulus G$$ G $$, Young's modulus E$$ E $$, Pugh ratio B/G$$ B/G $$, Poisson's ratio v$$ v $$, and anisotropy factor A$$ A $$. Because the bulk modulus responds linearly to pressure, the material's hardness increases as pressure rises. Additionally, under pressures up to 40 GPa, the optical characteristics of RhTiP, including their reflectivity, absorptivity, conductivity, dielectric constant, refractive index, and loss function, were assessed and discussed. Furthermore, the thermoelectric properties are also studied for the materials and supports the tunning of pressure. This study provides a gateway to how the optoelectronic and transport properties of cubic RhTiP could be tuned by employing external pressure. [ABSTRACT FROM AUTHOR]

Kagome metal ScV6Sn6 has been a subject of interest due to the emergence of a first-order structural phase transition with intriguing charge density wave behavior below the transition temperature Tc ∼ 92 K. To explore the thermoelectric properties and provide experimental insights into the nature of the phase transition, we have carried out a combined study by means of the electrical resistivity, Seebeck coefficient, and thermal conductivity measurements on single crystalline ScV6Sn6. Pronounced features near Tc have been characterized by all measured physical quantities. In particular, the Seebeck coefficient exhibits a marked reduction as lowering temperature across Tc, attributed to an imbalance of the contribution from different type of carriers induced by the structural phase transition. From the examination of the electronic and lattice thermal conductivities, we obtained a confirmation that the observed enhancement at Tc is essentially caused by the change of the lattice thermal conductivity, demonstrating the primary importance of lattice distortions for the heat transport of ScV6Sn6. In addition, the lattice thermal conductivity above Tc was found to increase monotonically with temperature. We associated the peculiar phenomenon with lattice fluctuations, highlighting the essence of structural instability in the kagome lattice ScV6Sn6. These results add to the knowledge about the thermal transport properties in kagome materials with a hexagonal HfFe6Ge6-type structure. [ABSTRACT FROM AUTHOR]

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