Synergistical Enhancement of Thermoelectric Properties in n-Type Bi2O2Se by Carrier Engineering and Hierarchical Microstructure
Synergistical Enhancement of Thermoelectric Properties in n-Type Bi2O2Se by Carrier Engineering and Hierarchical Microstructure
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载流子工程和分级微结构协同增强n型Bi2O2Se热电性能
DOI：
10.1002/aenm.201900354
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发表时间：
2019
影响因子：
27.8
通讯作者：
Nan Ce-Wen
中科院分区：
文献类型：
--
作者：
Tan Xing;Liu Yaochun;Liu Rui;Zhou Zhifang;Liu Chan;Lan Jin-Le;Zhang Qinghua;Lin Yuan-Hua;Nan Ce-Wen
含氧化合物因其化学稳定性和热稳定性而成为很有前途的热电材料。与高性能的p型材料（例如，BiCuSeO的ZT≈1.5）相比，由于n型含氧材料的导电性和高导热性，其TE性能的增强仍然具有挑战性。本文报道了n型层状Bi2O2Se作为一种潜在的TE材料，其导热性和电输运性能可以通过载流子工程和分层微观结构有效地调整。用Ta掺杂剂选择性修饰[Bi2O2]2+绝缘层，可使载流子浓度提高4个数量级（从1015增加到1019cm−3），同时保持较高的载流子迁移率，从而大大提高功率因数（≈451.5µW K−2m−1）。同时，Ta的掺杂可以诱导晶格的分层结构，原子点缺陷、5-10 nm纳米点和亚微米级晶粒可以增强声子散射，从而逐渐抑制晶格的热导率。因此，在773 K时，Bi1.90Ta0.10O2Se的zt值达到0.36，比原始Bi2O2Se提高了约350%。在500 ~ 823 K范围内的平均zt30值在n型含氧TE材料中表现突出。这项工作为提高含氧化合物的ztvalue提供了一种理想的方法。
Oxygen‐containing compounds are promising thermoelectric (TE) materials for their chemical and thermal stability. As compared with the high‐performance p‐type counterparts (e.g.,ZT≈1.5 for BiCuSeO), the enhancement of the TE performance of n‐type oxygen‐containing materials remains challenging due to their mediocre electrical conductivity and high thermal conductivity. Here, n‐type layered Bi2O2Se is reported as a potential TE material, of which the thermal conductivity and electrical transport properties can be effectively tuned via carrier engineering and hierarchical microstructure. By selective modification of insulating [Bi2O2]2+layers with Ta dopant, carrier concentration can be increased by four orders of magnitude (from 1015to 1019cm−3) while relatively high carrier mobility can be maintained, thus greatly enhancing the power factors (≈451.5 µW K−2m−1). Meanwhile, the hierarchical microstructure can be induced by Ta doping, and the phonon scattering can be strengthened by atomic point defects, nanodots of 5–10 nm and grains of sub‐micrometer level, which progressively suppresses the lattice thermal conductivity. Accordingly, theZTvalue of Bi1.90Ta0.10O2Se reaches 0.36 at 773 K, a ≈350% improvement in comparison with that of the pristine Bi2O2Se. The averageZTvalue of 0.30 from 500 to 823 K is outstanding among n‐type oxygen‐containing TE materials. This work provides a desirable way for enhancing theZTvalues in oxygen‐containing compounds.