Complex electronic structure and compositing effect in high performance thermoelectric BiCuSeO
Complex electronic structure and compositing effect in high performance thermoelectric BiCuSeO
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高性能热电BiCuSeO中复杂电子结构及复合效应
DOI：
10.1038/s41467-019-10476-7
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发表时间：
2019-06-27
影响因子：
16.6
通讯作者：
Nan, Ce-Wen
中科院分区：
文献类型：
--
作者：
Ren, Guang-Kun;Wang, Shanyu;Nan, Ce-Wen
BiCuSeO氧硒化物是有前途的热电材料，然而热电优值ZT的进一步改善在很大程度上受到较差的电输运性质的限制。关于这些材料的现有文献表明，在载流子浓度优化时，功率因数只有一个最大值，这对于大多数热电半导体来说是典型的。令人惊讶的是，我们发现三个功率因数最大值时，掺杂铋与铅。基于我们的第一性原理计算，数值模拟，和实验研究，我们归因于三个最大值的费米能量优化，能带收敛，复合效应，由于原位形成的PbSe沉淀。因此，在873 K下，对于4、10和14 at.%，实现了0.9、1.1和1.3的三个ZT峰Pb掺杂样品，分别揭示了BiCuSeO中Pb的复杂电子结构和多重作用的意义。结果建立一个准确的能带结构表征BiCuSeO和识别的作用带收敛和纳米沉淀的驱动机制，高ZT。
BiCuSeO oxyselenides are promising thermoelectric materials, yet further thermoelectric figure of merit ZT improvement is largely limited by the inferior electrical transport properties. The established literature on these materials shows only one power factor maximum upon carrier concentration optimization, which is typical for most thermoelectric semiconductors. Surprisingly, we found three power factor maxima when doping Bi with Pb. Based on our first-principles calculations, numerical modeling, and experimental investigation, we attribute the three maxima to the Fermi energy optimization, band convergence, and compositing effect due to in situ formed PbSe precipitates. Consequently, three ZT peaks of 0.9, 1.1, and 1.3 at 873 K are achieved for 4, 10, and 14 at.% Pb-doped samples, respectively, revealing the significance of complex electronic structure and multiple roles of Pb in BiCuSeO. The results establish an accurate band structure characterization for BiCuSeO and identify the role of band convergence and nanoprecipitation as the driving mechanism for high ZT.