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Scattering Mechanisms and Compositional Optimization of High‐Performance Elemental Te as a Thermoelectric Material
Advanced Electronic Materials ( IF 5.3 ) Pub Date : 2020-03-10 , DOI: 10.1002/aelm.202000038 Yehao Wu 1 , Qi Zhang 1 , Feng Liu 1 , Teng Fang 1 , Tiejun Zhu 1 , Xinbing Zhao 1
Advanced Electronic Materials ( IF 5.3 ) Pub Date : 2020-03-10 , DOI: 10.1002/aelm.202000038 Yehao Wu 1 , Qi Zhang 1 , Feng Liu 1 , Teng Fang 1 , Tiejun Zhu 1 , Xinbing Zhao 1
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p‐Type elemental tellurium (Te) has been found to be a promising thermoelectric (TE) material due to its high band degeneracy near the valence band maximum, and has exhibited a high zT ≈ 1.0 above 600 K. However, when forming Te1−xSex solid solutions, the maximal zTs are reduced because of the severely decreased carrier concentration. It is demonstrated that Se alloying is beneficial for enhancing TE performance of elemental Te provided the carrier concentration is optimized. Through Se alloying, the lattice thermal conductivity is remarkably suppressed by the induced large mass and strain field fluctuation, while the power factor can be maintained at a relatively high value as a result of the moderate alloying scattering potential, the unchanged density‐of‐state effective mass, and the optimized carrier concentration in Te1−xSex alloys. Notably, a positive temperature dependence of carrier mobility is observed near room temperature in Te1−xSex, which is proven to be caused by grain boundary scattering. A maximal zT ≈ 1.05 at 625 K is realized in Te0.93Se0.04As0.03 alloys, about 9% higher than the Se‐free Te. The conversion efficiency between 300 and 625 K is also improved ≈18% via Se alloying.
中文翻译：
高性能元素Te作为热电材料的散射机理及成分优化
p型元素碲（Te）因其在价带最大值附近的高带简并性而被发现是一种有前途的热电（TE）材料，并且在600 K以上具有较高的zT≈1.0。但是，形成Te 1时− x Se x固溶，最大zT由于载流子浓度大大降低，使s减小。结果表明，通过优化载流子浓度，Se合金化有利于增强元素Te的TE性能。通过Se合金化，诱导的大质量和应变场波动显着抑制了晶格热导率，而由于中等的合金散射势，不变的态密度，功率因数可以保持在较高的值Te 1- x Se x合金中的有效质量和最佳载流子浓度。值得注意的是，在室温下，Te 1- x Se x中载流子迁移率与温度呈正相关被证明是由晶界散射引起的。Te 0.93 Se 0.04 As 0.03合金在625 K时实现了最大的zT≈1.05，比不含Se的Te高约9％。通过Se合金化，在300和625 K之间的转换效率也提高了≈18％。
更新日期：2020-03-10
中文翻译：
高性能元素Te作为热电材料的散射机理及成分优化
p型元素碲（Te）因其在价带最大值附近的高带简并性而被发现是一种有前途的热电（TE）材料，并且在600 K以上具有较高的zT≈1.0。但是，形成Te 1时− x Se x固溶，最大zT由于载流子浓度大大降低，使s减小。结果表明，通过优化载流子浓度，Se合金化有利于增强元素Te的TE性能。通过Se合金化，诱导的大质量和应变场波动显着抑制了晶格热导率，而由于中等的合金散射势，不变的态密度，功率因数可以保持在较高的值Te 1- x Se x合金中的有效质量和最佳载流子浓度。值得注意的是，在室温下，Te 1- x Se x中载流子迁移率与温度呈正相关被证明是由晶界散射引起的。Te 0.93 Se 0.04 As 0.03合金在625 K时实现了最大的zT≈1.05，比不含Se的Te高约9％。通过Se合金化，在300和625 K之间的转换效率也提高了≈18％。
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