一周热电速览|09.17-09.23

摘要：Interfacial robustness at thermoelectric–electrode junctions, characterized by exceptional elevated-temperature chemical stability and mechanical integrity, emerges as a critical determinant for the operational longevity of devices. Despite the proven efficacy of barrier layers in mitigating interfacial chemical reaction/diffusion, large-scale fabrication of strongly bonded thermoelectric–barrier–electrode interfaces remains a formidable challenge. In this study, we demonstrate a controllable and reproducible fabrication of Ni electrodes and Ti barrier layers on Bi2Te3-based thermoelectric materials via an industrially scalable magnetron sputtering process. Impressively, an in situ formed nano-interlayer creates atomic bonding at all heterojunctions, achieving an outstanding bonding strength of ∼23 MPa with a competitively low contact resistivity of ∼21 μΩ cm2 at the junctions. These eventually enable one-pair thermoelectric modules to achieve a ∼53 K cooling effect at the hot-side temperature of ∼298 K and a sustained ∼4.8% conversion efficiency at a temperature gradient of ∼180 K. This work demonstrates a universal fabrication route for constructing robust interfaces across multiple functional layers in thermoelectric devices.

摘要：An innovative strategy is discovered to enhance the properties of bismuth-tellurium-based thermoelectric materials, aiding their development in power generation and solid-state refrigeration. The incorporation of trace Yb into the Bi0.4Sb1.6Te3 alloy significantly enhances its thermoelectric performance, notably boosting electrical transport properties through the induction of band splitting, resulting in a superior power factor 53 µW cm−1 K−2 at room-temperature and the figure of merit zT values 1.46 at 373 K. Second, Tin (Sn) doping is further introduced to create resonant levels. The microstructural analysis revealed that the coexistence of grain boundaries, nanoscale precipitates, and many stacking faults significantly increases the number of phonon-scattering sites, leading to an effective reduction in the lattice thermal conductivity. Consequently, the peak value of zT for the Yb & Sn co-doped p-type bismuth telluride reaches 1.48 at 373 K. Moreover, a single-leg power generation module fabricated from Material 1 is developed, achieving a conversion efficiency of 6.35% at a temperature difference of 214 K, and an eight-pair cooling module made from Material 2 demonstrated a cooling temperature difference of 75.8 K at a load of 350 K.

摘要：High energy conversion performance and sufficient flexibility are of great significance for widening the applications of thermoelectric devices (TEDs), yet the inferior compatibility between them needs to be deeply optimized. In this work, similar dimensionless figure of merit (ZT) values have been maintained for Bi2Te3-based constituents with strengthened phonon scattering, further assembling optimized flexible TEDs (F-TEDs). Thus, a maximum ZT value of 1.2 at 373 K has been implemented for p-type Bi 0.5Sb 1.5Te3 material, where the related thermal conductivity gradually reduced by modifying the grain size. Subsequently, a 200-pair F-TED with a packing factor of 35% has been delivered, where the open-circuit voltage and power density can achieve 3.0 V and 13.8 mW cm−2 at the temperature difference of 73 K, respectively. After a stretching test at the bending radius of 5 mm, the TED remains complete and ascertains excellent electrical stability and structural reliability. Besides, the height and weight have been decreased by 70% and 75%, as compared to those of the pristine TED. Therefore, the attributes of comfort and high flexibility have been endowed through halving the leg height and applying the high-density strategy, further boosting the practicality of Bi2Te3-based F-TEDs for wearable applications.

摘要：Thermoelectric conversion technology, capable of directly converting heat into electricity and vice versa, plays a crucial role in both energy supply and temperature control [1]. This is particularly crucial in specialized fields, such as deep-space exploration where solar power is ineffective, as well as in miniaturized precision temperature control applications [2]. Nevertheless, the conversion efficiency remains persistently suboptimal due to inherent energy dissipation mechanisms and limitations imposed by the material’s dimensionless figure of merit (ZT), typically confining efficiencies to single-digit percentages. Consequently, minimizing thermoelectric depletion has emerged as a critical research priority. This is especially pertinent for current and future applications in 5G/6G communications and artificial intelligence [3].

摘要：The earth-abundant tin sulfide (SnS) has emerged as an ecologically sustainable alternative for the thermoelectric community recently. However, its wide bandgap (≈46 kBT) is unfavorable for electrical performance, while the high vapor pressure of the S often results in a relatively low yield of synthesis. In this study, a synergistic strategy is devised to optimize the thermoelectric performance of polycrystalline SnS prepared via a low-temperature solid-state synthesis method. First, silver doping increases the hole carrier concentration (n) to ≈1019 cm−3. Subsequently, through selenium alloying, a dual-effect can be achieved: the bandgap is narrowed to increase the doping efficiency, while atomic point defects are introduced to lower the thermal conductivity. Ultimately, the polycrystalline Sn0.98Ag0.02S0.55Se0.45 attains a maximum ZT value of ≈0.9 at 873 K. The study indicates that promising thermoelectric performance can be obtained by a rapid synthesis method through a series of meticulously designed optimization strategies. This achievement offers novel insights and paves the way for the development of sulfide-based thermoelectrics.

摘要：Recent advancements in p-type SnS-based compounds have highlighted their potential for thermoelectric applications. Nevertheless, the thermoelectric properties of their n-type counterparts lag behind and have been seldom investigated to date, primarily owing to intrinsic Sn vacancies and limited donor dopability, which largely hinders the development of all SnS-based thermoelectric modules. Here, an effective doping strategy is proposed in n-type SnS-based polycrystals by incorporating PbSe along with a donor Br dopant. The electron concentration and power factor of PbSe alloyed compounds outperforms that of the matrix sample, being primarily credited to the improved dopability of Br dopant arising from the lower formation energy of Br dopant in the alloyed samples, as verified by first-principles calculations. Furthermore, the incorporation of PbSe remarkably diminishes the lattice thermal conductivity of the SnS-based materials, resulting from depressed phonon velocity, strengthened lattice anharmonicity and introduction of massive point defects. Consequently, an outstanding maximum zT value of ∼1.25 at 873 K, along with a decent average zT of ∼0.45 from 323 K to 873 K is attained in n-type 2.5%PbBr2-doped (SnS)0.6(PbSe)0.4 polycrystalline sample, representing record-high values in n-type SnS-based compounds. This research not only reveals that the optimal n-type SnS-based polycrystals are promising candidates for thermoelectric applications, but also offers insights into overcoming the doping bottleneck in thermoelectric materials.

摘要：We challenge the conventional design paradigm by demonstrating that light doping in single crystals can more effectively enhance the average ZT. A large-sized PbSe single crystal lightly doped with Sb was successfully grown via physical vapor deposition. By eliminating grain-boundary and point-defect scattering, the PbSb0.001Se crystal achieves a high electron mobility of 1,050 cm2 V−1 s−1 and a moderate carrier concentration of 1 × 1019 cm−3 at room temperature. This significantly improves thermoelectric performance over a wide temperature range. The optimized sample was fabricated into a 7-pair cooling device, achieving a temperature difference of 49 K at room temperature. Additionally, a single-leg device demonstrated a power generation efficiency of 8%. These results highlight how lightly doped single crystals provide a promising pathway to achieving high average ZT, making PbSe a competitive Te-free candidate for efficient thermoelectric cooling and power generation.

摘要：SnTe has attracted significant research interest as a lead-free alternative to PbTe; however, its intrinsically high hole concentration results in an undesirably low Seebeck coefficient and elevated electronic thermal conductivity, thus significantly limiting its thermoelectric (TE) performance. Herein, we present a cost-effective, binary thiol-amine-mediated colloidal synthesis method to synthesize Bi-doped SnTe nanoparticles, eliminating the use of tri-n-octylphosphine-based precursors. The introduction of an electron-rich Bi dopant reduces the hole concentration and increases the Seebeck coefficient. Furthermore, post-synthetic surface treatment with chalcogenidocadmate complexes promotes atomic interdiffusion during annealing and consolidation, leading to compositional redistribution and modulation of the electronic band structure. Density functional theory (DFT) calculations reveal that co-modification via Bi doping and CdSe-derived chalcogen incorporation reduces the energy offset at the valence band maxima from 0.30 eV to 0.10 eV, thereby enhancing valence band degeneracy. The synergistic structural and electronic band structure modulations produce an SnTe-based material with a record high power factor of 2.1 mW m–1 K–2 at 900 K, a maximum TE figure of merit (zT) of 1.2, and a promising theoretical conversion efficiency of 8.3%. This study reports a versatile and scalable colloidal synthesis strategy that integrates hierarchical structural modulation with electronic band engineering, offering a synergistic route to significantly enhance the TE performance.

摘要：Topological Heusler ferromagnets have emerged as a promising material platform for realizing a large anomalous Nernst effect (ANE) due to their intrinsic Berry curvature. This work reports a significantly enhanced ANE in polycrystalline bulk Co2MnAl1-xSix, enabled by synergistic tuning of atomic ordering and Fermi level via Si substitution. A large anomalous Nernst thermopower of 4.9 µV K−1 and an anomalous Nernst conductivity of 1.46 A m−1 K−1 at 300 K are obtained in Co2MnAl0.69Si0.31. Furthermore, A centimeter-sized bulk Nernst thermoelectric generator has been developed using Co2MnAl0.69Si0.31 as the legs, which delivers an output voltage of 2.2 mV and a maximum power of 7.7 µW under a temperature difference of 15 K. These results highlight the potential of scalable, high-performance polycrystalline topological magnets for transverse thermoelectric applications and pave the way for practical integration of ANE-based devices.

摘要：Thermoelectric cooling around liquid nitrogen temperature is vital to electronics and optoelectronics. This application calls for both high thermoelectric performance and superior mechanical properties to ensure decent deformability and processibility, which is nonetheless largely overlooked. In this work, the excellent temperature-induced plasticity of Bi0.85Sb0.15 as the classic liquid-nitrogen-temperature thermoelectric material is reported. The material shows large compressive strains exceeding 60% above ≈423 K, as well as a decent compressive strain of ≈21.5% at room temperature. By microstructural and atomistic analyses, the plasticity at slightly elevated temperature is ascribed mainly to the grain elongation and reorientation, which is rooted in the thermally amplified atomic vibration and thus reduced slip barrier energy. The low brittle-to-ductile transition temperature allows the material to be warm-processed into desired shapes in a metal-like manner with high efficiency and low losses. Particularly, the warm-extruded Bi0.85Sb0.15 shows comparably high thermoelectric performance as well as larger strength and compressibility as compared to the original bulks. These findings enable warm metalworking to promote the development of miniaturized and hetero-shaped thermoelectric cooling techniques around liquid nitrogen temperature.

摘要：Argyrodite compounds have garnered significant attention for their exceptional thermoelectric (TE) properties, with Ag8SnSe6 standing out as a prominent high-performance material, particularly at elevated temperatures. Ag8SnSe6 undergoes an order–disorder phase transition, which leads to the formation of a 3D percolation network of Ag ion transport in the disordered high-temperature phase. Despite significant interest in the TE properties of Ag8SnSe6, systematic experimental studies on its crystal structures, particularly the local structure in the disordered and ordered states and Ag ion migration pathways, remained largely unexplored. This study focuses on the structural evolution during phase transition and Ag ion diffusion at elevated temperatures. Synchrotron X-ray total scattering is utilized to systematically study the crystal structure and local atomic environment, especially across the phase transition. Additionally, synchrotron single-crystal X-ray diffraction is combined with the maximum entropy method (MEM) to provide a detailed analysis of the Ag ion migration pathways. The findings clarify the specific Ag diffusion channels connecting different Ag ions in Ag8SnSe6, offering valuable structural insights that serve as a benchmark for understanding the TE properties.

摘要：Thermoelectric technologies enable the direct solid-state conversion of heat into electricity, but performance improvement is challenging due to the strong interdependences among parameters. Here, the grain boundary-based energy filtering effect is explored to selectively scatter the low-energy carriers and thus enhance the Seebeck coefficient without degrading other properties. A superionic-induced fluid-like plastic deformation mechanism is utilized to fabricate dense and flexible Ag2Se films at a very low temperature (≈150 °C), which not only effectively sinters nanoparticles, but is also sufficiently low to maintain a high density of effective grain boundaries by suppressing excess fusing. The success of this low-temperature fusion process is attributed to the existence of excess Ag atoms, which serve as fusing agents to enhance the plastic deformation and thus facilitate the formation of closely contacted grains. As a result, the grain boundaries between those close-contacted grains boost the energy filtering effect while maintain the high electric conductivity, and therefore the obtained Ag2Se films achieve an outstanding Seebeck coefficient of −215 µV K−1 and a high power factor of 2500 µW m−1 K−2 at room temperature, representing a significant advancement in room temperature thermoelectric materials.

摘要：Liquid Cu2Se thermoelectric materials hold significant potential due to their intrinsically low thermal conductivity. In this study, a series of Ge-doped Cu2Se samples were synthesized using mechanical alloying and spark plasma sintering techniques. The investigation focused on examining the effects of Ge doping on the thermoelectric performance and stability of Cu2Se. The introduction of Ge reduces Cu vacancies and promotes the formation of Cu2Se/Ge heterojunctions within the matrix. These heterojunctions act as filters for low-energy carriers, thereby optimizing carrier concentration. They also increase dislocation density, enhance phonon scattering, and reduce thermal conductivity. Furthermore, the Cu2Se/Ge interface forms a Schottky barrier, preventing the long-range migration of Cu+ ions, which enhances the material’s stability. As a result, the ZT value reached 2.44 at 823 K, representing a 114% improvement. Furthermore, the nano-secondary phase and grain refinement have increased the compressive strength by four times, providing crucial support for equipment engineering.

摘要：Low thermal conductivity (κ) is an important physical parameter inherent to all solids, and the quest for intrinsic ultralow-κ solids is one of the key scientific issues. Material design based on functional units can achieve control over lattice and phonon dynamics, and it is proposed that asymmetric structural units-mediated van der Waals stacking can collectively lead to the low thermal conductivity. Herein, a novel van der Waals material In2G2Se₆ is reported, in which the distorted InSe₆ octahedron forms monolayers in conjunction with Ge2Se₆ dimers, which are further stacked along the c-axis via weak metavalent bonding. The distorted octahedron and van der Waals stacking result in large anharmonicity and ultrasoft acoustic phonon along Γ–Z direction, respectively. Consequently, In2Ge2Se6 exhibits ultralow out-of-plane thermal conductivity, κout-of-plane ≈0.2 W m−1K−1 at 600 K. This study establishes a model for phonon physics that simultaneously enhances phonon-phonon scattering and lowers the phonon group velocity, revealing the great potential of functional-unit-based material design for low-κ solids.

摘要：Thermoelectric generators (TEGs) demonstrate significant potential for sustainable energy harvesting through direct heat-to-electricity conversion. Nevertheless, conventional fully encapsulated designs face critical limitations including heat dissipation inefficiencies and restricted conformability to complex curved surfaces. This investigation proposes a breakthrough bidirectional π-structured (BDπ-structure) that achieves enhanced mechanical compliance while establishing a mechano-electrical coupling criterion for abrupt curvature transitions. Through implementing a reverse design framework integrating 3D scanning and curvature distribution analysis, customized topological configurations are specifically developed and adapted to target heat source geometries. Concurrently, a novel photocurable composite with enhanced thermal conductivity (0.213 W·m−1·K−1) is designed through 3D-printed structural optimization, achieving 59.1% power enhancement compared to conventional encapsulated modules. Experimental validation demonstrates remarkable surface fit tightness of 90.7% (positive Gaussian) and 80.2% (negative Gaussian), translating to exceptional power output improvements of 432.7% and 253.2% relative to non-optimized counterparts. This work establishes a comprehensive framework encompassing material innovation, structural design, and system integration strategies, significantly advancing flexible thermoelectric technology for high-efficiency energy harvesting from geometrically complex thermal sources.

摘要：High-sensitivity thermoresponsive materials are pivotal in intelligent temperature sensing for early warning, particularly when main power fails. Thermoelectric (TE) materials are advantageous for such scenario-based application, yet those with suitable flexibility, sensitivity and robustness for multifunctional sensing remain challenging due to intrinsic brittleness of pristine inorganic TE materials. Here, a robust temperature sensor based on a Bi2Se3 TE film in situ synthesized with PEDOT:PSS (P@Bi2Se3) is developed. This subtle optimization delivers substantial improvement to traditional TE films, with a power factor of 154.7 µW mK−2 at 440 K (three times that of pristine Bi2Se3), the highest among reported flexible Bi2Se3/organic TE films. In addition, the film shows excellent flexibility and stability, with barely 6% conductivity loss after 2000 bendings and 29% stability improvement over pristine Bi2Se3 films. A sensor assembled with this TE film demonstrates outstanding sensitivity and response at 94% efficiency within 1 s. Beyond thermal sensing, the film demonstrates great energy storage potential shown by a Zn//P@Bi2Se3 battery with zero capacity decay after 200 cycles. This facilely prepared hybrid TE film integrating efficient thermoelectric conversion, flexibility and energy storage shows full-scale advantages over its inorganic analogue, providing solutions for intelligent temperature monitoring in medical assistance and battery safety.

摘要：Two sugar-based block copolymers (BCPs), maltotriose-block-polystyrene (MT-PS) and maltoheptaose-block-polystyrene (MH-PS), comprise varying oligosaccharide and polystyrene block lengths. The inherent amphiphilic characteristics of these BCPs enable efficient dispersion of carbon nanotubes (CNTs) in both N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF). These solvents prove instrumental in the fabrication of BCP/CNT thin films, yielding both p-type and n-type nanocomposites. Through optimization of processing conditions, the resultant nanohybrids exhibit tremendous enhancement of thermoelectric properties, with figure of merit (zT) reaching 9.10 × 10−3 and 8.78 × 10−3 at 303 K for p-type and n-type materials, respectively. Molecular Dynamics (MD) simulations confirm the effective interfacial adhesion between the sugar-based BCPs and CNTs. Detailed structural and spectroscopic analyses elucidate the correlation between solvent selection and thermoelectric performance. These findings highlight the potential of this new class of sugar-based BCP/CNT nanocomposites as efficient materials for thermoelectric applications, offering insights into the role of solvent-mediated interactions in optimizing nanocomposite functionality for energy harvesting technologies.

摘要：Graphene has emerged as a paradigmatic material in condensed matter physics due to its exceptional electronic, mechanical, and thermal properties. A deep understanding of its thermoelectric transport behavior is crucial for the development of novel nanoelectronic and energy-harvesting devices. In this work, we investigate the thermoelectric transport properties of monolayer graphene subjected to randomly distributed localized strain fields, which locally induce impurity-like perturbations. These strain-induced impurities are modeled via 2D Dirac oscillators, capturing the coupling between pseudorelativistic charge carriers and localized distortions in the lattice. Employing the semiclassical Boltzmann transport formalism, we compute the relaxation time using a scattering approach tailored to the Dirac oscillator potential. From this framework, we derive analytical expressions for the electrical conductivity, Seebeck coefficient, and thermal conductivity. The temperature dependence of the scattering centers density is also investigated. Our results reveal how strain modulates transport coefficients, highlighting the interplay between mechanical deformations and thermoelectric performance in graphene. This study provides a theoretical foundation for strain engineering in thermoelectric graphene-based devices.

摘要：The thermoelectric materials could play a crucial role in fuel production for a circular economy, as they could provide a method to utilize the photons of relatively low energy from thermalization losses of light absorption. However, the traditional thermoelectric property was enhanced through optimizing the inherent band engineering according to the Seebeck coefficient, which ignored the off-centering behavior of the conduction band under the light. Herein, we exploited the thermal conversion characteristics of covalent organic framework-1,3,5-triformylphloroglucinol 3,8-diamino-6-phenylphenanthridine (COF-TpDPP) under red light to construct a three-component photoelectric material (WO3/COF-TpDPP/CdS). Through the Kelvin probe force microscope and density functional theory calculations, the COF-TpDPP layer reduced carrier transport barriers under the illumination of red light through the off-centering behavior of the conduction band to form thermoelectric and band-gap compression effects. As a result, the COF-TpDPP facilitated carrier transport between WO3 and CdS by utilizing its thermoelectric properties to reconstruct the carrier migration pathway, thereby creating a heat-mediated charge transfer system analogous to a “ship-lock” mechanism, which caused a 30% enhancement in photocurrent. Additionally, the photocatalytic degradation capability of WO3/COF-TpDPP/CdS has been utilized to develop a device for measuring soluble total organic carbon. This new mechanism presents approaches for the design of advanced thermoelectric materials in enhancing photo-electrocatalytic efficiency for the application in energy management, the treatment of hazardous waste, and environmental monitoring.

摘要：The self-powered and ultra-broadband photodetectors based on the photothermoelectric (PTE) effect hold significant promise for diverse applications, including night vision, environmental monitoring, and gas sensing. However, existing PTE materials, primarily based on 2D or bulk materials, face limitations in flexible applications and large-area array integration. Here, it is demonstrated that a flexible PTE photodetector constructed from a large-area bismuth telluride (Bi2Te3) film, coupled with an asymmetric electrode structure. The temperature gradient generated by the asymmetric electrode configuration induces carrier diffusion, resulting in the generation of photovoltage via the PTE effect, even under global illumination. The device exhibits broadband photoresponse across the spectral range from 0.405 to 10.37 µm at room temperature, achieving a detectivity of 1.39 × 108 Jones at 10.37 µm. Furthermore, the photodetector is integrated into a gas-sensing system, achieving a limit of detection (LOD) of ≈100 ppm for CO2 in its self-powered mode without external circuits. This work paves the way for the development of flexible, CMOS-compatible, and cost-effective optical gas sensors with integrated multifunctionality.

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