Trace bismuth and iodine co-doping enhanced thermoelectric performance of PbTe alloys

Abstract

Lead telluride (PbTe) is an excellent thermoelectric material in the intermediate temperature zone and has been applied to deep space exploration, waste heat recovery and other fields. However, the low thermoelectric conversion efficiency of the n-type PbTe alloys limits its applications. Here, the thermoelectric performances have been enhanced in n-type PbTe alloys through trace bismuth (Bi) and iodine (I) co-doping. The Pb1−xBixTe1−xIx (x = 0.00%, 0.05%, 0.10%, 0.20% and 0.50%) alloys are synthesized in the single phase compounds by a stepwise synthesis method. The carrier concentration has reached an optimal concentration range within the order of 1019 cm−3. The highest absolute Seebeck coefficient of 244 μV/K is obtained for 0.05% doped alloy at 730 K. The highest absolute Seebeck coefficient leads to high power factor for 0.05% doped, especially in low- and middle-temperature range. The highest power factor ∼25 μW K−2 cm−1 has been obtained at 329 K. Complex micro-scale grain boundaries and point defects strongly increase the phonon scattering and then lead to the lowest lattice thermal conductivity of 0.64 W mK−1 at 674 K for x = 0.50%, which is 26% lower than that of pristine PbTe. As a result, the highest figure of merit, zT ∼ 0.9 has been determined in 0.20% doped samples at 725 K. Moreover, the highest average figure of merit, zTave ∼ 0.7 has been achieved in 0.05% doped samples in the 323–723 K temperature range, which is about two or three times higher than reported for single Bi or I doped PbTe samples.

Enhancing Thermoelectrics for Small-Bandwidth n-Type PbTe–MnTe Alloys via Balancing Compromise

“…The integration of the reduced electrical conductivity and the improved Seebeck coefficient contributes to a tremendous enhancement of PF in the Cu-intercalated PbTe–MnTe samples, especially at room temperature, ranging from ∼2.37 mW m –1 K –2 (0.1% Cu) to ∼3.07 mW m –1 K –2 (0.5% Cu); the temperature-dependent PF for all samples can be seen in Figure S1 in Supporting Information. As shown in Figure c, compared with the experimental value reported in the literature, ,,,,, the PF of Cu-intercalated samples maintains a higher value in the whole temperature range, consistent with the theoretical prediction, but a value lower than the predicted value from another report due to the increased inertial effective mass in PbTe–MnTe alloys. In particular, the PF of Cu-doped PbTe–MnTe alloys in this work at room temperature is much higher than that of conventional np 3 donor Sb-doped PbTe–MnTe alloys, while the PF at an elevated temperature is still equivalent …”

“…Specifically, the optimal carrier concentration ( n H , opt ) at 773 K (5.2 × 10 19 cm –3 ) differs from that at 323 K (7.8 × 10 18 cm –3 ) by nearly an order of magnitude. However, the constant carrier concentration through the conventional np 3 donor impurity is seriously inconsistent with the optimal value near room temperature. ,,− Therefore, we further carried out Hall measurements on all Cu-intercalated samples. It can be observed from Figure b that the carrier concentration of all Cu-intercalated samples has little difference at room temperature due to the low solubility of Cu in PbTe.…”

“…Due to the symmetry crystal structure and large lattice anharmonicity, lead chalcogenide PbTe is widely utilized as a thermoelectric material in the medium-temperature region (500–900 K). , This inspires numerous efforts to improve the peak and average thermoelectric figures of merit of n-type PbTe materials to achieve a higher conversion efficiency. − However, the thermoelectric parameters are strongly coupled with each other, the compromise between carrier concentration and Seebeck coefficient ( n / S ), − the trade-off between effective mass and carrier mobility (μ/ m b * ), − even the only relatively independent parameter, and the lattice thermal conductivity, also contradictory to the carrier mobility (μ/κ l ), , which make it challenging to obtain the net enhancement of zT. Therefore, the solution of the aforementioned compromises among the thermoelectric parameters is of significance and necessary.…”

A Review on Fundamentals, Design and Optimization to High ZT of Thermoelectric Materials for Application to Thermoelectric Technology

“…7. Similarly Na and Ag in SnSe, 100 Bi-and I-doped PbTe 101 and Pt in half-Heusler (HH) NbCoSn 102 were effective dopants that enhanced the thermoelectric properties as summarized in Fig. 7.…”

Fungus Bran-Derived Porous N-Doped Carbon–Zinc Manganese Oxide Nanocomposite Positive Electrodes toward High-Performance Asymmetric Supercapacitors

“…Environmental pollution and energy shortages caused by fossil fuel consumption have led to an urgent need to replace fossil fuels with sustainable energy sources to reduce their harmful effects. − Supercapacitors are a type of device for renewable energy storage. − During the charging and discharging process of electrical double-layer capacitors (EDLCs), electrolyte ions store charges through reversible electrostatic adsorption and desorption, and no redox chemical reactions occur . Therefore, EDLCs have high power density and long cycling stability.…”