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  1. Future advancements in three-dimensional (3D) electronics require robust thermal management methodology. Thermoelectric coolers (TECs) are reliable and solid-state heat pumping devices with high cooling capacity that can meet the requirements of emerging 3D microelectronic devices. Here, we first provide the design of TECs for electronics cooling using a computational model and then experimentally validate the main predictions. Key device parameters such as device thickness, leg density, and contact resistance were studied to understand their influence on the performance of TECs. Our results show that it is possible to achieve high cooling power density through optimization of TE leg height and packing density. Scaling of TECs is shown to provide ultra-high cooling power density.
  2. Thermoelectric materials could play a crucial role in the future of wearable electronic devices. They can continuously generate electricity from body heat. For efficient operation in wearable systems, in addition to a high thermoelectric figure of merit, zT, the thermoelectric material must have low thermal conductivity and a high Seebeck coefficient. In this study, we successfully synthesized high-performance nanocomposites of n-type Bi2Te2.7Se0.3, optimized especially for body heat harvesting and power generation applications. Different techniques such as dopant optimization, glass inclusion, microwave radiation in a single mode microwave cavity, and sintering conditions were used to optimize the temperature-dependent thermoelectric properties of Bi2Te2.7Se0.3. The effects of these techniques were studied and compared with each other. A room temperature thermal conductivity as low as 0.65 W/mK and high Seebeck coefficient of −297 μV/K were obtained for a wearable application, while maintaining a high thermoelectric figure of merit, zT, of 0.87 and an average zT of 0.82 over the entire temperature range of 25 °C to 225 °C, which makes the material appropriate for a variety of power generation applications.
  3. Abstract

    Thermoelectric (TE) generators enable the direct and reversible conversion between heat and electricity, providing applications in both refrigeration and power generation. In the last decade, several TE materials with relatively high figures of merit (zT) have been reported in the low‐ and high‐temperature regimes. However, there is an urgent demand for high‐performance TE materials working in the mid‐temperature range (400–700 K). Herein, p‐type AgSbTe2materials stabilized with S and Se co‐doping are demonstrated to exhibit an outstanding maximum figure of merit (zTmax) of 2.3 at 673 K and an average figure of merit (zTave) of 1.59 over the wide temperature range of 300–673 K. This exceptional performance arises from an enhanced carrier density resulting from a higher concentration of silver vacancies, a vastly improved Seebeck coefficient enabled by the flattening of the valence band maximum and the inhibited formation of n‐type Ag2Te, and ahighly improved stability beyond 673 K. The optimized material is used to fabricate a single‐leg device with efficiencies up to 13.3% and a unicouple TE device reaching energy conversion efficiencies up to 12.3% at a temperature difference of 370 K. These results highlight an effective strategy to engineer high‐performance TE material in the mid‐temperature range.

    Free, publicly-accessible full text available December 24, 2023
  4. Thermal energy harvesting from natural resources and waste heat is becoming critical due to ever-increasing environmental concerns. However, so far, available thermal energy harvesting technologies have only been able to generate electricity from large temperature gradients. Here, we report a fundamental breakthrough in low-grade thermal energy harvesting and demonstrate a device based on the thermomagnetic effect that uses ambient conditions as the heat sink and operates from a heat source at temperatures as low as 24 °C. This concept can convert temperature gradients as low as 2 °C into electricity while operating near room temperature. The device is found to exhibit a power density (power per unit volume of active material) of 105 μW cm −3 at a temperature difference of 2 °C, which increases to 465 μW cm −3 at a temperature difference of 10 °C. The power density increases by 2.5 times in the presence of wind with a speed of 2.0 m s −1 . This advancement in thermal energy harvesting technology will have a transformative effect on renewable energy generation and in reducing global warming.