Bi2O2Se oxyselenides, characterized with intrinsically low lattice thermal conductivity and large Seebeck coefficient, are potential n-type thermoelectric material in the mediate temperature range. Given the low carrier concentration of ~1015 cm−3 at 300 K, the intrinsically low electrical conductivity actually hinders further enhancement of their thermoelectric performance. In this work, the isovalent Te substitution of Se plays an effective role in narrowing the band gap, which notably increases the carrier concentration to ~1018 cm−3 at 300 K and the electron conduction activation energy has been lowered significantly from 0.33 eV to 0.14 eV. As a consequence, the power factor has been improved from 104 μW·K−2·m−1 for pristine Bi2O2Se to 297 μW·K−2·m−1 for Bi2O2Se0.96Te0.04 at 823K. Meanwhile, the suppressed lattice thermal conductivity derives from the introduced point defects by heavier Te atoms. The gradually decreased phonon mean free path reflects the increasingly intense phonon scattering. Ultimately, the ZT value attains 0.28 for Bi2O2Se0.96Te0.04 at 823K, an enhancement by a factor of ~2 as compared to that of pristine Bi2O2Se. This study has demonstrated that Te-substitution of Se could synergistically optimize the electrical and thermal properties thus effectively enhancing the thermoelectric performance of Bi2O2Se. This article is protected by copyright. All rights reserved.

中文翻译：

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通过Te取代协同优化Bi2O2Se陶瓷的电和热传输性能

Bi2O2Se 氧硒化物具有固有的低晶格热导率和大塞贝克系数，是中等温度范围内潜在的 n 型热电材料。鉴于在 300 K 时的低载流子浓度约为 1015 cm-3，固有的低电导率实际上阻碍了其热电性能的进一步增强。在这项工作中，Se 的等价 Te 取代在缩小带隙方面发挥了有效作用，在 300 K 时将载流子浓度显着增加到~1018 cm-3，并且电子传导激活能从 0.33 eV 显着降低到 0.14 EV。因此，功率因数从原始 Bi2O2Se 的 104 μW·K-2·m-1 提高到 823K 时 Bi2O2Se0.96Te0.04 的 297 μW·K-2·m-1。同时，受抑制的晶格热导率源自较重的 Te 原子引入的点缺陷。逐渐减少的声子平均自由程反映了越来越强烈的声子散射。最终，Bi2O2Se0.96Te0.04 在 823K 时的 ZT 值达到 0.28，与原始 Bi2O2Se 相比提高了约 2 倍。该研究表明，Te 取代 Se 可以协同优化电学和热学性能，从而有效提高 Bi2O2Se 的热电性能。本文受版权保护。版权所有。与原始 Bi2O2Se 相比，提高了约 2 倍。该研究表明，Te 取代 Se 可以协同优化电学和热学性能，从而有效提高 Bi2O2Se 的热电性能。本文受版权保护。版权所有。与原始 Bi2O2Se 相比，提高了约 2 倍。该研究表明，Te 取代 Se 可以协同优化电学和热学性能，从而有效提高 Bi2O2Se 的热电性能。本文受版权保护。版权所有。