Superior Conversion Efficiency Achieved in GeP3/h-BN Heterostructures as Novel Flexible and Ultralight Thermoelectrics.
Superior Conversion Efficiency Achieved in GeP3/h-BN Heterostructures as Novel Flexible and Ultralight Thermoelectrics.
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DOI：
10.1021/acsami.1c01860
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发表时间：
2021-04
影响因子：
9.5
通讯作者：
Shuai Duan;Yangfan Cui;Wen-cai Yi;Xin Chen;Bingchao Yang;Xiaobing Liu
中科院分区：
文献类型：
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作者：
Shuai Duan;Yangfan Cui;Wen-cai Yi;Xin Chen;Bingchao Yang;Xiaobing Liu
GeP3材料由于其典型的褶皱层结构、高载流子迁移率和化学稳定性而引起了广泛的研究兴趣。这种特性加速了各向异性电导和热导的独立控制，因此有望具有很大的热电势。然而，由于低塞贝克系数，GeP3在大块和厚膜中的金属特性不利于实际应用。因此，迫切需要探索有效的解决方案来扩大带隙，同时保持其优异的导电性。在此，我们设计了不同厚度的GeP3/六方氮化硼（h-BN）交错体异质结构。通过基于玻尔兹曼输运理论的从头计算，我们发现封盖h-BN层可以使GeP3层的带隙明显增加0.24 eV，更有趣的是，GeP3/h-BN异质结构中的各向异性电子结构相应地向有利于高热电性的方向调制。在300 K时，p型GeP3/h-BN的ZT值高达5左右，这是由于调整后的多谷能带结构所致。总的来说，我们的工作提供了一条有效的途径，通过适当的异质结构来设计新的高性能热电材料。
GeP3 materials are attracting broad research interest due to their typical puckered layer structure, high carrier mobility, and chemical stability. This peculiarity expedites the independent control of anisotropic electrical and thermal conductance, which is thus expected to possess great thermoelectric potential. Nevertheless, the metal characteristics of GeP3 in the bulk and thick films are adverse to real application because of the low Seebeck coefficient. Thus, it is highly desirable to explore effective solutions to broaden the band gap and also maintain its excellent electrical conductance. Herein, we designed the interlaced GeP3/hexagonal boron nitride (h-BN) bulk heterostructure using various component thicknesses. By using ab initio calculations based on the Boltzmann transport theory, we found that capping h-BN layer can obviously increase the band gap of the GeP3 layer by 0.24 eV, and more interestingly, the anisotropic electronic structure in the GeP3/h-BN heterostructure was accordingly modulated toward a favorable direction for high thermoelectricity. An ultrahigh ZT value of around 5 was predicted at 300 K in p-type GeP3/h-BN, attributed to the adjusted multivalley band structure. Overall, our work provided an effective route to design novel high-performance thermoelectrics through the appropriate construction of heterostructures.