Abstract 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.

中文翻译：

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二维黑磷纳米片增强热电性能的预测

摘要 由于独特的层状结构，黑磷 (BP) 为热电应用提供了相对独立控制电导率和热导率的可能性。因此，尽管体块 BP 的能量转换效率低和结构不稳定性，但将高性能 BP 基热电材料作为柔性无毒和超轻器件实现是非常有趣的。在这项工作中，我们通过第一性原理计算和玻尔兹曼输运理论系统地研究了从单层到四层的二维 BP 的热电性质。从计算中可以得出结论，通过调整层厚可以有效优化 BP 纳米片的热电性能。我们发现 300 和 500 K 的最大 ZT 值可以达到 0.45 和 0。沿扶手椅方向在 p 型双层 BP 中分别为 90，比室温下的体高约 5 倍。双层 BP 的高性能主要归功于其高度各向异性和简并载流子口袋。因此，我们进一步提出 BP/h-BN 异质结构的形成可以在 500 K 下将 ZT 提高至 1.2，这有利于薄 BP 在柔性和环保热电材料中的实际应用。