PbSe is an attractive thermoelectric material due to its favorable electronic structure, high melting point, and lower cost compared to PbTe. Herein, the hitherto unexplored alloys of PbSe with NaSbSe2(NaPb
Thermoelectrics operating at high temperature can cost-effectively convert waste heat and compete with other zero-carbon technologies. Among different high-temperature thermoelectrics materials, silicon nanowires possess the combined attributes of cost effectiveness and mature manufacturing infrastructures. Despite significant breakthroughs in silicon nanowires based thermoelectrics for waste heat conversion, the figure of merit (
- NSF-PAR ID:
- 10252301
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract m SbSem +2) are described and the most promising p‐type PbSe‐based thermoelectrics are found among them. Surprisingly, it is observed that below 500 K, NaPbm SbSem +2exhibits unorthodox semiconducting‐like electrical conductivity, despite possessing degenerate carrier densities of ≈1020cm−3. It is shown that the peculiar behavior derives from carrier scattering by the grain boundaries. It is further demonstrated that the high solubility of NaSbSe2in PbSe augments both the thermoelectric properties while maintaining a rock salt structure. Namely, density functional theory calculations and photoemission spectroscopy demonstrate that introduction of NaSbSe2lowers the energy separation between the L‐ and Σ‐valence bands and enhances the power factors under 700 K. The crystallographic disorder of Na+, Pb2+, and Sb3+moreover provides exceptionally strong point defect phonon scattering yielding low lattice thermal conductivities of 1–0.55 W m‐1K‐1between 400 and 873 K without nanostructures. As a consequence, NaPb10SbSe12achieves maximumZT ≈1.4 near 900 K when optimally doped. More importantly, NaPb10SbSe12maintains highZT across a broad temperature range, giving an estimated recordZT avgof ≈0.64 between 400 and 873 K, a significant improvement over existing p‐type PbSe thermoelectrics. -
Abstract The rapid enhancement of the thermoelectric (TE) figure‐of‐merit (
zT ) in the past decade has opened opportunities for developing and transitioning solid state waste heat recovery systems. Here, a segmented TE device architecture is demonstrated in conjunction with heterogeneous material integration that results in high unicouple‐level conversion efficiency of 12% under a temperature difference of 584 K. This breakthrough is the result of success in fabricating bismuth telluride/half‐Heusler segmented TE unicouple modules using a “hot‐to‐cold” fabrication technique that provides significantly reduced electrical and thermal contact resistance. Extensive analytical and finite element modeling is conducted to provide an understanding of the nature of thermal transport and contributions arising from various thermal and physical parameters. Bismuth telluride/half‐Heusler based segmented thermoelectric generators (TEGs) can provide higher practical temperature difference with optimum averagezT across the whole operating range. These results will have immediate impact on the design and development of TEGs and in the general design of devices based upon heterostructures that take advantage of gradients in the figure of merit. -
Abstract Printing is a versatile method to transform semiconducting nanoparticle inks into functional and flexible devices. In particular, thermoelectric nanoparticles are attractive building blocks to fabricate flexible devices for energy harvesting and cooling applications. However, the performance of printed devices are plagued by poor interfacial connections between nanoparticles and resulting low carrier mobility. While many rigid bulk materials have shown a thermoelectric figure of merit
ZT greater than unity, it is an exacting challenge to develop flexible materials withZT near unity. Here, a scalable screen‐printing method to fabricate high‐performance and flexible thermoelectric devices is reported. A tellurium‐based nanosolder approach is employed to bridge the interfaces between the BiSbTe particles during the postprinting sintering process. The printed BiSbTe flexible films demonstrate an ultrahigh room‐temperature power factor of 3 mW m−1K−2andZT about 1, significantly higher than the best reported values for flexible films. A fully printed thermoelectric generator produces a high power density of 18.8 mW cm−2achievable with a small temperature gradient of 80 °C. This screen‐printing method, which directly transforms thermoelectric nanoparticles into high‐performance and flexible devices, presents a significant leap to make thermoelectrics a commercially viable technology for a broad range of energy harvesting and cooling applications. -
Abstract An emerging chalcogenide perovskite, CaZrSe3, holds promise for energy conversion applications given its notable optical and electrical properties. However, knowledge of its thermal properties is extremely important, e.g. for potential thermoelectric applications, and has not been previously reported in detail. In this work, we examine and explain the lattice thermal transport mechanisms in CaZrSe3using density functional theory and Boltzmann transport calculations. We find the mean relaxation time to be extremely short corroborating an enhanced phonon–phonon scattering that annihilates phonon modes, and lowers thermal conductivity. In addition, strong anharmonicity in the perovskite crystal represented by the Grüneisen parameter predictions, and low phonon number density for the acoustic modes, results in the lattice thermal conductivity to be limited to 1.17 W m−1 K−1. The average phonon mean free path in the bulk CaZrSe3sample (
N → ∞) is 138.1 nm and nanostructuring CaZrSe3sample to ~10 nm diminishes the thermal conductivity to 0.23 W m−1 K−1. We also find that p-type doping yields higher predictions of thermoelectric figure of merit than n-type doping, and values ofZT ~0.95–1 are found for hole concentrations in the range 1016–1017 cm−3and temperature between 600 and 700 K. -
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 (zT max) of 2.3 at 673 K and an average figure of merit (zT ave) 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.