Abstract:Since 2010, we have evidenced the very promising thermoelectric properties of layered oxychalcogenides, with parent compound BiCuSeO, which could be used in thermoelectric conversion systems in the 300-600 • C temperature range. These materials, that were first studied in the early 2000s for their optoelectronic properties, exhibit thermoelectric figure of merit values around 1.4 at 650 • C, which makes them the best lead-or tellurium-free p-type thermoelectric materials ever reported to date. In this paper, w… Show more
“…Similar large Hall mobility has also been obtained by Hidenori et al in the epitaxial thin film of Mg-doped LaCuSeO, a compound with the same degenerate state as that of BiCuSeO, and can be attributed to the enhancement of chemical bond-covalency and hybridization of the relevant anion orbitals [39, 40]. Moreover, the band dispersion close to the VBM is larger in BiCuSeO than in LaCuSeO [41], which will lead to smaller effective mass and larger Hall mobility.Fig. 4 a Carrier concentration n and mobility μ of the Bi 1 − x Ba x CuSeO (0 ≤ x ≤ 10%) thin films measured at room temperature.…”
We reported the epitaxial growth of c-axis-oriented Bi1−xBaxCuSeO (0 ≤ x ≤ 10%) thin films and investigated the effect of Ba doping on the structure, valence state of elements, and thermoelectric properties of the films. X-ray photoelectron spectroscopy analysis reveal that Bi3+ is partially reduced to the lower valence state after Ba doping, while Cu and Se ions still exist as + 1 and − 2 valence state, respectively. As the Ba doping content increases, both resistivity and Seebeck coefficient decrease because of the increased hole carrier concentration. A large power factor, as high as 1.24 mWm−1 K−2 at 673 K, has been achieved in the 7.5% Ba-doped BiCuSeO thin film, which is 1.5 times higher than those reported for the corresponding bulk samples. Considering that the nanoscale-thick Ba-doped films should have a very low thermal conductivity, high ZT can be expected in the films.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2752-6) contains supplementary material, which is available to authorized users.
“…Similar large Hall mobility has also been obtained by Hidenori et al in the epitaxial thin film of Mg-doped LaCuSeO, a compound with the same degenerate state as that of BiCuSeO, and can be attributed to the enhancement of chemical bond-covalency and hybridization of the relevant anion orbitals [39, 40]. Moreover, the band dispersion close to the VBM is larger in BiCuSeO than in LaCuSeO [41], which will lead to smaller effective mass and larger Hall mobility.Fig. 4 a Carrier concentration n and mobility μ of the Bi 1 − x Ba x CuSeO (0 ≤ x ≤ 10%) thin films measured at room temperature.…”
We reported the epitaxial growth of c-axis-oriented Bi1−xBaxCuSeO (0 ≤ x ≤ 10%) thin films and investigated the effect of Ba doping on the structure, valence state of elements, and thermoelectric properties of the films. X-ray photoelectron spectroscopy analysis reveal that Bi3+ is partially reduced to the lower valence state after Ba doping, while Cu and Se ions still exist as + 1 and − 2 valence state, respectively. As the Ba doping content increases, both resistivity and Seebeck coefficient decrease because of the increased hole carrier concentration. A large power factor, as high as 1.24 mWm−1 K−2 at 673 K, has been achieved in the 7.5% Ba-doped BiCuSeO thin film, which is 1.5 times higher than those reported for the corresponding bulk samples. Considering that the nanoscale-thick Ba-doped films should have a very low thermal conductivity, high ZT can be expected in the films.Electronic supplementary materialThe online version of this article (10.1186/s11671-018-2752-6) contains supplementary material, which is available to authorized users.
“…The most widely accepted concept is phonoglass electron‐crystal materials with intrinsically low κ l due to complex crystal structure, such as skutterudites and clathrates . In more recent years, strongly anisotropic SnSe and BiCuSeO have been evidenced possessing high electrical performance as well as low κ l and subsequently high zT due to layered structure . With liquid‐like behavior, superionic materials, such as Cu 2 X‐based (X = Te, Se, and S) thermoelectric materials, Ag 2 Se, and Ag 2 S, are also experiencing high zT with ultralow κ l .…”
Due to the nature of their liquid‐like behavior and high dimensionless figure of merit, Cu2X (X = Te, Se, and S)‐based thermoelectric materials have attracted extensive attention. The superionicity and Cu disorder at the high temperature can dramatically affect the electronic structure of Cu2X and in turn result in temperature‐dependent carrier‐transport properties. Here, the effective strategies in enhancing the thermoelectric performance of Cu2X‐based thermoelectric materials are summarized, in which the proper optimization of carrier concentration and minimization of the lattice thermal conductivity are the main focus. Then, the stabilities, mechanical properties, and module assembly of Cu2X‐based thermoelectric materials are investigated. Finally, the future directions for further improving the energy conversion efficiency of Cu2X‐based thermoelectric materials are highlighted.
“…Previous developments of thermoelectric materials were mainly focused on the intermetallics or alloys. Recently, oxide materials have gained some interest and a number of potential candidates were reported [6,7], including NaCo 2 O 4 [8], LaCoO 3 [9], CaMnO 3 [10], SrTiO 3 [11], and BiCuSeO [12,13]. Especially, the layerstructured BiCuSeO and its doped samples seem to have a high ZT comparable to the above alloys.…”
Section: Introductionmentioning
confidence: 99%
“…The reported ZT of the BiCuSeO based compounds ranges between 0.68 and 1.4 at the measurement temperature 873e923 K [12e21]. The high ZT is reported to arise from its high Seebeck coefficient (~420 mVK À1 at 923 K) and low thermal conductivity (~0.34 Wm À1 K À1 at 923 K) [12,13], while its electrical conductivity is moderate.…”
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