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SiGe based alloy is a promising medium-high temperature thermoelectric material that has been applied in the field of aerospace exploration. So far, utilizing the second phase to promote the scattering of phonons is a common way to improve the thermoelectric performance of SiGe based alloy, but this often deteriorates the electrical properties. In this study, the Si80Ge20P1/CoSi2 composites have been prepared by mechanical alloying and spark plasma sintering, and the content of cobalt silicide (CoSi2) nanoparticles have been manipulated. Since the CoSi2 nanoparticles possess higher carrier concentration and smaller work function than the Si80Ge20P1 matrix, the carrier concentrations of composites have been pushed up due the charge transfer effect. Meanwhile, the formation of nano-sized phase interfaces and stacking faults in the composites has enhanced the scattering of low-frequency phonons. As a result, the optimal power factor of 3.41 mW⋅m−1⋅K−2 and thermal conductivity of 2.29 W⋅m−1⋅K−1 have been achieved, and the corresponding zT reaches up to 1.3 in the Si80Ge20P1+0.5% CoSi2 (in mole) composite at 873 K. This work provides a new idea for developing the performance of SiGe based alloy.

SiGe is recognised as an excellent thermoelectric material with superior mechanical properties and thermal stability in regions with high temperatures. This study explores a novel strategy for co-regulating thermoelectric transport parameters to achieve high thermoelectric properties of p-type SiGe in the mid-temperature region by incorporating nano-TaC into SiGe combined ball milling with spark plasma sintering. By optimizing the amount of TaC in the SiGe matrix, the power factors were significantly increased due to the modulation doping effect based on the work function matching of SiGe with TaC. Simultaneously, the ensemble effect of the nanostructure leads to a significant decrease in thermal conductivity. Thus, a high ZT of 1.06 was accomplished at 873 K, which is 64 % higher than that of typical radioisotope thermoelectric generator. Our research offers a novel strategy for expanding and enhancing the thermoelectric properties of SiGe materials in the medium temperature range.

Si-based thermoelectric (TE) materials are exhibiting remarkable perspectives in self-energized applications with their special advantages. However, the relatively high total thermal conductivity (κ) prevents their TE enhancement. Here, a strategy of co-compositing dual oxides was implemented for enhancing the TE properties of p-type Si80Ge20 bulks. Composited Ga2O3 was demonstrated to enhance the power factor (PF) due to the crystallization-induced effect of produced Ga by decomposition on SiGe matrix. Associating with compositing SiO2 aerogel (a-SiO2) powder, not only introduced the fine amorphous inclusions and decreased the grain size of host matrix, but also various nano morphologies were formed, i.e., nano inclusions, precipitations, twin boundaries (TBs), and faults. Combining with the eutectic Ge, hierarchical scattering centers impeded the phonon transport comprehensively (decreasing the phonon group velocity (va) and relaxation time) for reducing the lattice-induced thermal conductivity (κl). As a result, a minimum κ of 2.38 W·m−1·K−1 was achieved, which is significantly dropped by 32.6% in contrast with that of the pristine counterpart. Ultimately, a maximal dimensionless figure of merit (ZT) of 0.9 was achieved at 600 ℃, which is better than those of most corresponding oxide-composited Si-based bulks.

In this study, a micro in-plane p-type thermoelectric generator (TEG), which consists of thin-film Si1−x−yGexSny ternary alloy semiconductor on insulator, is developed to make efficient use of waste heat such as human body. A power factor value as high as 1095 μWm−1K−2 had been achieved using B-ion implanted and short-term rapid thermal annealing (RTA) process. In addition, a measuring scheme for micro TEG without external load resistance was designed. In one measuring session, multiple parameters can be measured. The micro single-arm TEG prepared by semiconductor process can output 0.29 nW power at a temperature difference of 15 K, and a cross-sectional power density has reached up to 0.58 mW/cm2, which is a superior value for wearable device. The findings of this study have important reference value for wearable device performance improvement and output power measuring of micro TEG.

Summary: Silver selenide is considered as a promising room temperature thermoelectric material due to its excellent performance and high abundance. However, the silver selenide-based flexible film is still behind in thermoelectric performance compared with its bulk counterpart. In this work, the composition of paper-supported silver selenide film was successfully modulated through changing reactant ratio and annealing treatment. In consequence, the power factor value of 2450.9 ± 364.4 μW/(mK2) at 303 K, which is close to that of state-of-the-art bulk Ag2Se has been achieved. Moreover, a thermoelectric device was fabricated after optimizing the length of annealed silver selenide film via numerical simulation. At temperature difference of 25 K, the maximum power density of this device reaches 5.80 W/m2, which is superior to that of previous film thermoelectric devices. Theoretically and experimentally, this work provides an effective way to achieve silver-selenide-based flexible thermoelectric film and device with high performance. : Electrochemical Materials Science; Materials Synthesis; Energy Materials Subject Areas: Electrochemical Materials Science, Materials Synthesis, Energy Materials