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GeTe has been considered as a promising mid‐temperature thermoelectric (TE) candidate, but its zT value is severely limited by the excessive hole concentration and high thermal conductivity. Here, it is demonstrated that the TE properties of GeTe can be significantly improve by defect engineering of Sb‐Pb and AgCuTe codoping. The Sb‐Pb codoping is adopted to optimize the carrier concentration and manipulate the rhombohedral lattice distortion, leading to valence band convergence and enhanced power factor. The AgCuTe alloying introduces multiscale phonon scattering centers including dislocations and nano‐precipitates to reduce the lattice thermal conductivity in GeTe. Consequently, a maximum zT of 2.3 at 773 K and an average zT of 1.43 (300–773 K) are obtained in (Ge0.84Sb0.06Pb0.1Te)0.99(AgCuTe)0.01. Moreover, the fabricated thermoelectric module exhibits a high output power density of 0.59 W cm–2 and an energy conversion efficiency of 7.9% at ΔT = 500 K, suggesting hierarchical defect engineering is an effective strategy to realize high‐performance GeTe‐based thermoelectric. [ABSTRACT FROM AUTHOR]

Bi2Te3‐based alloys have historically dominated the commercial realm of near room‐temperature thermoelectric (TE) materials. However, the more widespread application is currently constrained by its mediocre TE performance and inferior mechanical properties resulting from intrinsic hierarchical structure. Herein, microstructure modulation and carrier transport optimization strategies are employed to efficiently balance the electro‐thermal transport performance. Specifically, the weighted mobility increases by 24%, while the lattice thermal conductivity decreases by 31% at 350 K compared to the matrix. Consequently, the Bi0.5Sb1.496Cu0.004Te2.98 sample attains a peak ZT of 1.45 at 350 K and an average ZT of 1.20 (300–500 K). Moreover, intricated microstructure design, exemplified by the gradient twin structure, significantly enhances the mechanical performance metrics, including Vickers hardness, compressive strength, and bending strength, to notable levels of 0.94 GPa, 224 MPa, and 58 MPa, respectively. Consequently, the constructed 17‐pair TE modules demonstrate a maximum conversion efficiency of 6.5% at ΔT = 200 K, surpassing the majority of reported Bi2Te3‐based modules. This study provides novel insights into the synergistic enhancement of TE and mechanical properties in Bi2Te3‐based materials, with potential applicability to other TE systems. [ABSTRACT FROM AUTHOR]

A flexible thermoelectric device (F-TED) possesses two distinct advantages: harvesting residual heat from the human body to power electronic devices and regulating body temperature to achieve thermal comfort states. These unique merits have sparked widespread research into their application in personal thermal management (PTM). However, inorganic and thin-film TEDs suffer from drawbacks such as limited power output and complex fabrication processes. Here, we have developed a foldable, high-performance F-TED based on bismuth telluride with polyimide as the substrate and polydimethylsiloxane as the encapsulation material. The F-TED demonstrates an open-circuit voltage of up to 404 mV, an output power of 80 mW, and a power density of 9 mW cm−2 at ΔT = 50 K, respectively. In further PTM experiments, the copper foam is employed as a heatsink to effectively maintain the F-TED temperature difference. The modified F-TED exhibits a consistently increased output power of over 40% across different air velocities compared to the F-TED without the heatsink, and it also realizes stable skin temperatures during skin cooling, demonstrating significant potential for application in PTM. [ABSTRACT FROM AUTHOR]

The thermoelectric performance of p-type PbTe was found to be superior to that of n-type PbTe, mainly owing to the successful band engineering of the p-type materials. Here, we report a novel band engineering effect, namely temperature-dependent impurity level, in n-type PbTe achieved by In and Cu2Te co-doping. Above 700 K, the co-doped material exhibited an uncommon increase in the Seebeck coefficient, which is very different from the behavior of the single Cu2Te- and In-doped compounds. We show that the thermoelectric transport of the co-doped compound can be explained by the temperature-dependent impurity level as In produces the impurity level state and Cu2Te ensures proper carrier concentration. Owing to the optimization of the power factor by the impurity level, the co-doped compound exhibited a peak zT of 1.5 at 773 K and an average zTavg of 0.94. The thermoelectric performance was further examined by fabricating a thermoelectric module containing seven pairs of legs. [ABSTRACT FROM AUTHOR]

As a benchmark for commercial room-temperature thermoelectric (TE) materials, the widespread demand for recovering distributed low-grade waste heat (below 573 K) underscores the immediate necessity for advanced Bi2Te3-based alloys. Here, we achieved a 22% enhancement of the peak ZT to 1.43 at 325 K by incorporating highly reactive additive Cu2SnTe3 into Bi0.5Sb1.5Te3, which is notably higher than that of most BixSb2−xTe3-based composites. This remarkable enhancement is facilitated by the in situ reaction of decomposition products with the matrix, thereby boosting hole concentration and the density-of-states effective mass, while experiencing little loss in hole mobility. Simultaneously, the lattice thermal conductivity is significantly reduced by multiscale scattering sources, typical of dislocation arrays and Sb and Cu-rich nanoprecipitates. These synergistic results yield a 30% enhancement of the TE quality factor at 300 K, reaching 0.52 for the optimal Bi0.5Sb1.5Te3 + 0.08 wt% Cu2SnTe3 sample. More significantly, when coupled with n-type zone-melted Bi2Te2.7Se0.3, the well-designed 17-pair TE module achieves a conversion efficiency of ∼6.0%, surpassing the majority of reported Bi2Te3-based modules, which further demonstrates the efficacy of the Cu2SnTe3 compositing strategy and the great potential for practical applications. [ABSTRACT FROM AUTHOR]

Power generation modules utilizing thermoelectric (TE) materials are suitable for recycling widespread low‐grade waste heat (<600 K), highlighting the immediate necessity for advanced Bi2Te3‐based alloys. Herein, the substantial enhancement in TE performance of the p‐type Bi0.4Sb1.6Te3 (BST) sintered sample is realized by subtly incorporating the non‐stoichiometric Ag5Te3 and counteractive Se. Specifically, Ag atoms diffused into the BST lattice improve the density‐of‐states effective mass (md*) and boost the hole concentration for the suppressed bipolar effect. The addition of Se further improves md* prompting the room‐temperature power factor upgrade to 46 W cm−1 K−2. Concurrently, the lattice thermal conductivity is considerably lowered by multiple scattering sources exemplified by Sb‐rich nanoprecipitates and dense dislocations. These synergistic results yield a high peak ZT of 1.44 at 375 K and an average ZT of 1.28 between 300 and 500 K in the Bi0.4Sb1.6Te2.95Se0.05 + 0.05 wt.% Ag5Te3 sample. More significantly, when coupled with n‐type zone‐melted Bi2Te2.7Se0.3, the integrated 17‐pair TE module achieves a competitive conversion efficiency of 6.1% and an output power density of 0.40 W cm−2 at a temperature difference of 200 K, demonstrating great potential for practical applications. [ABSTRACT FROM AUTHOR]

The thermal-electric conversion efficiency is a crucial metric for evaluating the performance of a thermoelectric generator (TEG). However, accurate measurement of this efficiency remains a significant challenge due to various factors that impact heat flow measurements. We have observed that temperature fluctuations during temperature control are the primary factor contributing to measurement errors in heat flow under vacuum conditions. To address this issue, we have developed a time-dependent theoretical model for the thermal-electric coupling of a TEG measurement system based on Fourier's theory of heat conduction. This model allows us to investigate the effects of both temperature fluctuation and structural parameters on the measurement error of TEG performance. Furthermore, we have proposed an error correction scheme for TEG performance based on our theoretical and experimental findings. These insights provide a theoretical framework and technical guidance for more precise measurements of TEG performance. [ABSTRACT FROM AUTHOR]