Prediction of enhanced thermoelectric performance in two-dimensional black phosphorus nanosheets
Prediction of enhanced thermoelectric performance in two-dimensional black phosphorus nanosheets
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二维黑磷纳米片增强热电性能的预测
DOI：
10.1016/j.vacuum.2020.109790
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发表时间：
2021-01-01
期刊：
影响因子：
4
通讯作者：
Liu, Xiao-Bing
中科院分区：
文献类型：
--
作者：
Cui, Yang-Fan;Duan, Shuai;Liu, Xiao-Bing
由于其独特的层状结构，黑磷（BP）为热电应用提供了相对独立控制电导率和导热率的可能性。因此，尽管大块BP的能量转换效率低且结构不稳定，但实现基于BP的高性能热电器件作为柔性、无毒和超轻的器件是非常有意义的。本文采用第一性原理计算和玻尔兹曼输运理论，系统地研究了二维BP从单层到四层的热电性质。计算结果表明，调整BP纳米片的层厚可以有效地优化其热电性能。结果表明，在300 K和500 K时，p型双层BP沿扶手椅方向的ZT最大值分别可达0.45和0.90，约为室温下体积的5倍。双层BP的高性能主要归因于其高度各向异性和简并的载流子袋。因此，我们进一步提出BP/h-BN异质结构的形成可以在500 K时将ZT提高到1.2，这有利于薄BP在柔性和环保热电器件中的真正应用。
Because of the unique layered structure, black phosphorus (BP) provides a possibility of relatively independent control in electrical and thermal conductivity for thermoelectrical applications. It is therefore of great interest to realize high-performance BP-based thermoelectrics as flexible non-toxic and ultralight devices in spite of the low energy conversion efficiency and structural instability of the bulk BP. In this work, we systematically study the thermoelectric properties for the two-dimensional BP from mono-layer up to quad-layer by first-principles calculations and Boltzmann transport theory. It can be concluded from the calculations that the thermoelectric performance of BP nanosheets can be effectively optimized by tuning the layer thickness. We reveal that the maximum ZT values at 300 and 500 K can reach up to 0.45 and 0.90 in p-type bi-layer BP along armchair direction, respectively, around 5 times higher than that of the bulk at room temperature. The high performance in bi-layer BP is mainly attributed to its highly anisotropic and degenerate carrier pockets. Accordingly, we further propose that the formation of BP/h-BN heterostructure can enhance ZT up to 1.2 at 500 K, which facilitates the real application of thin BP for flexible and eco-friendly thermoelectrics.