Cation-sublattice disorder engineered by CdTe alloying governs phonon transport in CuInTe 2 through the synergistic effects of defect scattering and lattice softening.

Bi2Te3-based materials are the best commercial thermoelectric (TE) materials for applications near room temperature. However, zone-melted (ZM) materials suffer from poor mechanical properties, while traditional powder metallurgy-derived Bi2Te3 exhibits a strong donor-like effect when refined into fine grains, creating a fundamental barrier to the simultaneous enhancement of mechanical and TE performance. Herein, high-performance n-type Bi2Te3-based materials were fabricated via a hybrid process combining melt spinning (MS) and hot extrusion (HE). The MS-derived foils exhibit a strong (110) orientation, nanocrystalline structure, and no significant donor-like effect despite air exposure. These characteristics of these foils are maintained in the precursor for HE via rapid sintering by directly laying the foils flat without grinding. This strongly oriented, fine-grained characteristic of the ribbon precursor is inherited and further intensified via subsequent HE, which yields fine-grained, highly textured bulk materials with an orientation factor F-(110) of 0.54. The enhanced texture and microstructure result in a high carrier mobility of 348 cm(2)V-1s(-1) and a power factor of 52.20 mu Wcm(-1)K-2, while intensifying phonon scattering and reducing lattice thermal conductivity to 0.5 Wm(-1)K-1. Consequently, a peak ZT of 1.25 at 345 K and a room temperature ZT of 1.12 are achieved. This material also demonstrates exceptional mechanical properties, with a record-high compressive strength of 338 MPa and flexural strength of 153.8 MPa. This work resolves the longstanding trade-off between mechanical robustness and TE efficiency, enabling the fabrication of TE legs (<100 m) for large-scale applications. It paves the way for the fabrication of micro-TE devices.

Developing high-performance thermoelectric materials with intrinsically low lattice thermal conductivity and tunable electronic properties is critical for advancing efficient energy conversion technologies toward global sustainability. Herein, we report a pavonite compound Ag3Pb4Bi11Se22 integrating a unique quasi-superlattice architecture and naturally occurring quasi-high-entropy alloy characteristics. These structural features synergistically induce intense phonon scattering yielding an ultra-low lattice thermal conductivity of 0.32-0.57 W m-1 K-1 over the temperature range of 300-773 K. First-principles calculations reveal that Ag3Pb4Bi11Se22 is a narrow-bandgap semiconductor with a multi-valley conduction band featuring up to six closely spaced energy valleys. By tailoring the carrier concentration through controlled Se deficiency, the Fermi level is optimized to activate multi-valley cooperative transport, significantly enhancing the band degeneracy from 2 to 10 and the density of states effective mass from 0.6 m 0 to 1.8 m 0. This optimization mitigates the degradation of the Seebeck coefficient at high carrier concentrations while simultaneously improving electrical conductivity. Ultimately, the Ag3Pb4Bi11Se21.9 sample attains a maximum thermoelectric figure of merit (ZT) of 0.9 at 773 K. This work establishes Ag3Pb4Bi11Se22 as a benchmark pavonite-based thermoelectric material and offers a viable paradigm for optimizing complex chalcogenides via integrated structural engineering and band structure modulation.

In the packaging of bismuth telluride -based micro-thermoelectric coolers (TECs), identifying cost-effective interconnect solders to replace expensive Au-Sn alloys holds significant commercial value. This work systematically compares the high-temperature reliability and interfacial reaction mechanisms of cost-advantaged Sn-Sb solid solution solder versus conventional Au-Sn solder within micro-TECs. High-temperature aging tests conducted at 125 degrees C for 500 h demonstrate that TECs encapsulated with both solders satisfy the testing standards for telecommunication-grade devices. However, the performance degradation of Sn-Sb solder-based TECs was more pronounced than that of their Au-Sn counterparts, evidenced by a 9.2% reduction in shear strength. While the Au-Sn solder maintains a stable interface with Bi2Te2.7Se0.3, it facilitates the formation of Sb2Au nanoparticles at the Bi0.4Sb1.6Te3 contact site, which effectively inhibits Sn diffusion and preserves interfacial integrity. In contrast, the diffusion of Sn in Sn-Sb solder disrupts Bi-Te bonds within the Bi2Te2.7Se0.3 matrix, leading to the formation of SnTe, BiTe, and elemental Bi. Due to the high Bi content in the matrix, a thick BiTe transition layer is formed, accompanied by a 52.0% volume expansion. Furthermore, the layered crystal structure of Bi0.4Sb1.6Te3 is completely destroyed by Sn, yielding stable SnTe and SnSb; in this case, Bi exists only as sparse nanocrystalline grains and a thin BiTe transition layer, with the volume expansion rate reaching as high as 90.9%. Consequently, high-precision solder volume control and the implementation of a continuous, dense diffusion barrier process are essential prerequisites for the viable alternative application of Sn-Sb solders.

Bi2Te3-based materials prepared by traditional zone melting often have poor mechanical properties. Although powder metallurgy followed by hot extrusion can effectively enhance mechanical strength, this approach involves a lengthy, multi-step processes including powdering, sintering, and extrusion. Such a complex procedure s hinders the development of polycrystalline Bi2Te3-based materials and their application in micro-thermoelectric devices. In this work, p-type Bi2Te3-based ribbons are first fabricated via melt spinning. Subsequently, a series of highly textured, fine-grained p-type Bi2Te3-based bulk materials are prepared by directly tiling these ribbons and consolidating them through spark plasma sintering (SPS). The as-spun ribbon has a strong texture, as well as numerous nanostructures and defects. The subsequent consolidation, achieved by directly tiling these ribbons and applying SPS without any pulverization, effectively preserves their intrinsic preferred orientation. This results in a strong (110) texture perpendicular to the pressing direction, which is different from those obtained via the traditional ball-milling and SPS routes. The sample sintered at 743 K exhibits an orientation factor of 0.37, comparable to those of hot-extruded counterparts. Owing to this strong texture, the sample exhibits superior electrical transport properties along the direction parallel to the pressing direction. A high power factor of 3.79 mW & centerdot;m(-1)& centerdot;K-2 is achieved at room temperature. Furthermore, grain refinement leads to a significant reduction in thermal conductivity. Consequently, a peak ZT value of 1.30 is obtained at 398 K for the sample sintered at 743 K, representing a 46% enhancement over the ZT values of traditional zone-melted samples. This study provides a rapid and facile strategy for fabricating highly textured, fine-grained, high-performance Bi2Te3-based materials, thereby laying a solid foundation for their engineering applications in micro-thermoelectric devices.

O 2 physically adsorbs on defective PbTe, and then activates as the OO bond lengthens. Upon dissociation, one O atom occupies a V Te site. After lattice relaxation, the system stabilizes into a final O Te + V Pb defect complex.

The discovery of silver chalcogenides ductile semiconductors with high room-temperature plasticity holds significant promise for the development of bendable thermoelectric and electronic devices. However, the atomic-scale origins of their plasticity, ranging from dislocation slip to sublattice amorphization, remain diverse and material-specific. Here, we report a distinct deformation mechanism in Ag2Te through stress-driven and ionic-hop-mediated domain rotation. By in-situ scanning/transmission electron microscopy (S/TEM), we directly observe the hopping of Ag ions to adjacent vacancies stabilizes the deformed Te-sublattice and facilitates a coordinated ~92.2° lattice rotation that accommodates substantial plastic strain. This mechanism, which preserves long-range crystallinity, contrasts with both traditional dislocation-mediated plasticity and stress-induced amorphization pathways. Combined with its excellent thermoelectric performance (ZT value of ~0.67) at room temperature, Ag2Te emerges as a promising flexible electronic material.

Active control of heat flow is crucial for managing thermal energy in sustainable technologies. However, current technologies are limited by the small switching ratio and narrow operating temperature range of thermal switching materials. Herein, we demonstrate that molybdenum disulfide (MoS2) exhibits an excellent thermal switching performance across an ultra-wide temperature range of 300-1573 K, based on a reversible transition between the non-polarized hexagonal (2H) and electronically polarized rhombohedral (3R) phases. This phase transition is kinetically limited, and the presence of electric field lowers the transition barrier, dramatically reducing the temperature and pressure required to drive the phase transition. The application of the electric field results in a vertical flip from the out-of-plane alignment along the pressure direction in the 2H phase ("off" state) to an in-plane polarization alignment along the electric field direction in the 3R phase ("on" state). This phase transition and polarized orientation switching, in conjunction with the significant anisotropic thermal transport properties of both phases, lead to a record-high thermal switching ratio of 15.2 at 300 K and maintains 6.6 at 1573 K. Our findings provide a new avenue for exploring high-performance thermal switch material triggered by phase transition and orientation changes in highly anisotropic materials.

The superlattice engineering approach has proven effective in synergistically improving physical properties of multifunctional materials, yet its application in GeTe-based films remains unexplored. In this work, we fabricated (1T'-MoTe2)x/(GeTe)y superlattice films with well-controlled periodic layering and good structural coherence periodicity via molecular beam epitaxy, demonstrating the simultaneous optimization of thermoelectric and ferroelectric properties through superlattice engineering. The improved thermoelectric performance in GeTe-based superlattices arose from the evolution of intrinsic point defects, interfacial charge transfer, and band-bending-induced energy filtering. Specifically, the (1T'-MoTe2)2/(GeTe)80 film achieved a high carrier effective mass of 3.70 m* and a superior room-temperature power factor of 2.53 mW m-1 K-2, arising from an optimal balance between enhanced effective mass and hole density. Meanwhile, the (1T'-MoTe2)2/(GeTe)30 film exhibited markedly enhanced ferroelectric polarization as compared to the pristine GeTe film, with a large piezoelectric coefficient (d33) of 15.3 pm V-1, which is likely attributed to interfacial charge-transfer-induced suppression of the depolarization field. This work highlights the efficacy of superlattice engineering in concurrently optimizing thermoelectric and ferroelectric properties of GeTe-based films, offering insights on performance optimization of multifunctional materials.

Flexible thermoelectric devices offer a promising approach for harvesting low-grade waste heat from the human body to sustainably power wearable electronics. Here, a fully flexible thermoelectric generator (f-TEG) based on a sandwich architecture is presented, utilizing high-performance n-type Bi2Te2.7Se0.3 and p-type Bi0.5Sb1.5Te3 materials as the active thermoelectric units, with liquid metal serving as the electrode. This design circumvents the need for conventional surface metallization and intricate soldering processes. To enhance the substrate's thermal conductivity, a polydimethylsiloxane (PDMS) composite incorporating 20 wt % aluminum nitride (AlN) ceramic nanoparticles was employed for encapsulation. This approach yielded a thermal conductivity of 0.45 W m-1 K-1, approximately three times that of pure PDMS. The f-TEG devices demonstrated outstanding mechanical and electrical robustness, maintaining structural integrity and stable performance after 10,000 h of cyclic reorientation and 100,000 cycles of dynamic twisting. Moreover, both the thermoelectric materials and liquid metal could be nondestructively recovered and reused via simple mechanical peeling. As a proof of concept, the f-TEG units were monolithically integrated into a wearable belt. Powered solely by body heat at an ambient temperature of 25 °C, the integrated system stably delivered an output voltage of 180.6 mV. By incorporating a lightweight depthwise separable GRU network (DSGNet, 11.95 kB) that synergistically models features through depthwise separable convolutions and gated recurrent units, a posture recognition accuracy of 98.96% was achieved. This work establishes a feasible technological pathway toward constructing self-powered, intelligent human body protection systems that simultaneously offer long operational lifetime and facile manufacturability.

We report a high-performance thermoelectric pavonite compound, Ag0.5CdBi4.5Se8, featuring a unique quasi-superlattice structure assembled from five distinct polyhedral units ([AgSe6], [CdSe6], [(Bi1)Se5], [(Bi2)Se6], and [(Bi3)Se6]). Naturally arranged Bi-Se polyhedra with different distortions and crystallographic environments enable multidirectional orbital overlap, forming a quadruple-valley conduction band with a small energy separation of 0.07 eV. This electronic structure simultaneously enhances carrier transport and maintains a high Seebeck coefficient. Moreover, the inherently hybrid bonding network, which consists of alternating strong and weak bonds alongside coexisting ionic and covalent characters, combined with pronounced acoustic-optical phonon coupling originating from the [AgSe6]/[CdSe6] octahedra, results in an extremely low lattice thermal conductivity of 0.24 W m-1 K-1 at 823 K. While intrinsic Se vacancies render the pristine material an n-type degenerate semiconductor, Sb doping and Se-excess allow precise tuning of carrier concentration over a wide range (2.39 × 1019-4.81 × 1020 cm-3), enabling further optimization of electrical transport. At an optimal carrier concentration of 2.52 × 1020 cm-3, Ag0.5CdBi4.5Se8 achieves a peak thermoelectric ZT of 0.96 at 823 K, outperforming most previously reported pavonite derivatives. This work validates the utilization of the compound's intriguing multipolyhedral integration as a robust strategy to decouple electron-phonon transport, thereby providing insights for the rational design of high-performance thermoelectric materials.

Titanium diselenide (TiSe 2 ), a representative layered transition metal dichalcogenide (TMD), has emerged as a promising candidate for thermoelectric applications due to its unique structural characteristics, tunable electronic properties, and eco‐friendly composition. This review provides a comprehensive overview of the recent research progress on TiSe 2 ‐based thermoelectric materials. First, the fundamental structural features and intrinsic thermoelectric properties of TiSe 2 are summarized, including its layered crystal structure, charge density wave (CDW) transition, and intrinsic transport behaviors. Subsequently, various modulation strategies to enhance its thermoelectric performance are systematically discussed, such as chemical doping or intercalation, strain engineering, defect engineering, and heterostructure construction. The underlying mechanisms of performance enhancement, including band‐structure optimization, carrier‐concentration regulation, and lattice thermal conductivity reduction, are elaborated. Notably, a recently reported dual‐chemical strategy that simultaneously modifies intralayer bonding and interlayer charge dynamics is discussed in detail, as it yields an exceptionally high thermoelectric figure of merit ( ZT) of 0.82 in Cu 0.8 CrTi 2 Se 6 . This result underscores the potential of coordinated modulation strategies, although continued exploration of alternative dopant combinations and validation by independent groups remain important for establishing general design principles. Furthermore, the latest advances in TiSe 2 ‐based thermoelectric devices are briefly introduced. Finally, the current challenges and future development directions of TiSe 2 thermoelectric materials are prospected, aiming to provide guidance for the design and optimization of high‐performance TiSe 2 ‐based thermoelectric systems.

Conventional doping approaches for enhancing thermoelectric performance typically rely on multi-element co-doping, which complicates both the fabrication process and the interpretation of underlying mechanisms. In this study, we demonstrate that a single dopant, Sb, can effectively modulate the thermoelectric properties of PbSe through a concentration-dependent regulatory mechanism. Sb dopant at low concentrations (x <= 1.5 %) suppresses Pb vacancies in the structure which not only enhances doping efficiency but also maintains high carrier mobility at elevated carrier concentrations. All these significantly boost the electrical transport properties. In contrast, excess Sb induces additional Pb vacancies at higher concentration (x > 1.5 %), which reduce both carrier concentration and mobility. By suppressing the formation of Pb vacancy with low dose of Sb content, a significantly improved ZT(max) value of similar to 1.43 is attained at 785 K for Pb0.997Sb0.003Se sample, representing an approximately 2-fold improvement over the pristine PbSe (ZT(max) similar to 0.55).

GeBi2Te4-based materials have attracted considerable attention for thermoelectric applications due to their low lattice thermal conductivity, which arises from complex crystal structures and cation disorder. Point defect engineering serves as an effective strategy for optimizing the thermoelectric performance of GeBi2Te4. However, experimental characterization of point defects and their influence on electrical transport properties still requires further investigation. To address this issue, this study successfully fabricated a series of highly crystalline GeBi2Te4(000l )-based thin films on Al2O3 (000l ) substrates using the molecular beam epitaxy (MBE) technique. The Bi flux was systematically varied from 0.035 & Aring;/s to 0.075 & Aring;/s to investigate its role in tuning intrinsic point defects and inducing a possible phase transition. Scanning tunneling microscope (STM) measurements identified GeBi and TeBi antisite defects as the dominant point defects in GeBi2Te4. Angle-resolved photoemission spectroscopy (ARPES) is employed to probe the electronic band structure of GeBi2Te4 (000l) films, revealing linearly dispersive topological surface states across the bulk band gap and a Fermi level (EF) positioned within the conduction band. The electron density initially increased and subsequently decreased with increasing Bi flux, consistent with the EF shift trend observed by ARPES-likely due to the synergistic effect of p-type GeBi and n-type TeBi antisite defects. Moreover, when the Bi flux reached 0.075 & Aring;/s, the film underwent a phase transition from GeBi(2)Te(4 )to GeBi4Te7. The optimized GeBi(4)Te(7 )thin film exhibited the highest room-temperature carrier mobility of 48.2 cm(2)& centerdot;V-1 & centerdot;s(-1) among all samples, achieving excellent power factors of 1.3 mW & centerdot;m(-1)& centerdot;K-2 at 300 K and 1.7 mW & centerdot;m(-1)& centerdot;K-2 at 400 K-among the highest values reported for GeBi2Te4-based materials. The key findings of this work lie in the direct visualization of intrinsic point defects and the discovery of high-performance GeBi(4)Te(7 )with a high carrier effective mass. These results demonstrate that point defect engineering combined with phase structure regulation is effective for optimizing carrier transport and electrical properties in both GeBi2Te4-based materials.

The intrinsic coupling of thermoelectric parameters is a key factor limiting the enhancement of the dimensionless figure of merit (ZT). In this work, PbSe0.995Br0.005-x mol% BaTiO3 composites were prepared through spark plasma sintering at 823 K for 5 min. The results show a 40% significant improvement in the Seebeck coefficient, with stable electrical conductivity maintaining an excellent level of 3.7 x 10(5) S m(-1), as well as remarkably reduced lattice thermal conductivity close to PbSe's theoretical minimum. The sample with x = 1 achieves a maximum ZT of 1.40 at 873 K, which is driven by three synergistic mechanisms: ferroelectric energy filtering, dielectric environment enhancement, and enhanced phonon scattering from uniform BaTiO3 dispersion and interface acoustic impedance mismatch. This work highlights ferroelectric compositing as a robust approach for thermoelectric optimization.

Achieving intelligent human-computer interaction requires interfaces that are both highly integrated and reliable, capable of capturing subtle physiological and behavioral information from users. Flexible thermoelectric devices offer distinct advantages for low-power interactive applications, yet progress in system-level integration remains limited. Here, we report a monolithic integration strategy that combines thermopile arrays with analog-to-digital conversion circuits. By embedding the electrodes of flexible thermoelectric devices directly into the circuit layout, a fully integrated thermoelectric encoder is fabricated on a single polyimide substrate, consisting of four functional units. At an ambient temperature of 20 degrees C and a hot-side temperature of 35 degrees C, the device exhibits an open-circuit voltage of 21.2 mV and withstands over one million cycles of pressing and bending with less than 5% change in internal resistance. Using this encoder, three interaction states-hard press (similar to 1 N), light touch (similar to 0.3 N), and no contact-are distinguished, enabling a simple yet complete coding scheme that covers all 26 letters. To ensure robust operation across varying environmental conditions, a lightweight Tri-stream Spatiotemporal Fusion Network is introduced, with only 29292 parameters and a size of 114.4 kB. By integrating depthwise separable convolutions, bidirectional long short-term memory, and dynamic channel attention, this model achieves letter recognition accuracy exceeding 98%. Finally, the thermoelectric encoder is combined with an AI agent to demonstrate an intelligent interaction system for patient monitoring, supporting both daily assistance and emergency response.

Altermagnetic materials combine zero net magnetization with large spin splitting, offering new material platforms for spintronics. As the leading altermagnetic candidate, CrSb has been predicted to be a Weyl semimetal but lacks experimental evidence. Here, we report the controllable fabrication of high-quality CrSb (000l) thin films, leveraging optimized growth parameters and a novel Cr2SbTe buffer layer. Angle-resolved photoemission spectroscopy (ARPES) measurements provide definitive evidence of g-wave altermagnetic order, revealing a large band splitting of 0.54 eV near EF. The surface and altermagnetic band splitting are remarkably robust in CrSb thin films, as demonstrated from aspects of long-term storage, protective passivation layer strategy, and film thickness dependence. Moreover, magneto-transport measurements find no hallmark signatures of Weyl fermions, including the absence of negative chiral magnetoresistance and the specific scaling behavior of the planar Hall effect (PHE). This work establishes high-quality CrSb thin films as a robust platform for exploring altermagnetic phenomena and spintronic devices.