Abstract:

Phosphorene is a two-dimensional layered material with a special structure and has application prospects in the field of thermoelectrics. This study employed first-principles combined with density functional theory to investigate the thermal and electrical transport properties of bilayer heterostructures of phosphorene, comparing them with bilayer parallel phosphorene. The research revealed that the lattice thermal conductivity of phosphorene exhibits layer-dependent behavior due to interlayer van der Waals forces affecting out-of-plane phonon transport and increasing phonon group velocity. Disruption of crystal symmetry in bilayer antiparallel phosphorene leads to increased phonon scattering and decreased phonon group velocity, resulting in reduced lattice thermal conductivity. At 300 K, the lattice thermal conductivities for bilayer antiparallel phosphorene are ${\kappa }_{\mathrm{Z}\mathrm{Z}}$=113.251 W/(m·K) and ${\kappa }_{\mathrm{A}\mathrm{C}}$=32.315 W/(m·K). Increasing the number of layers in phosphorene reduces bandgap size and carrier scattering while enhancing its electrical transport performance. Compared to monolayer phosphorene, bilayer antiparallel phosphorene demonstrates higher thermoelectric figure of merit values; at 800 K in the AC direction, an N-type bilayer antiparallel phosphorene achieves a ZT value as high as 2.336. This study provides theoretical insights and references for regulating the performance of related thermoelectric materials.

Key words: nanomaterials, phosphorene, thermoelectric properties, first-principles, numerical simulation

摘要：

磷烯是一种具有特殊结构的二维层状材料，在热电领域具有应用前景。采用第一性原理，结合密度泛函理论，通过与双层同向磷烯的对比研究了双层异向磷烯异质结构的热电输运性能。研究表明，磷烯的晶格热导率具有层数依赖性，层间范德华力使面外声子输运受到影响，声子群速度增大。由于晶体结构的对称性受到破坏，双层异向磷烯的声子散射增加，声子群速度降低，导致晶格热导率降低。温度在300 K时，双层异向磷烯的晶格热导率为${\kappa }_{\mathrm{Z}\mathrm{Z}}$=113.251 W/(m·K)，${\kappa }_{\mathrm{A}\mathrm{C}}$=32.315 W/(m·K)。增加磷烯的层数，会导致能带带隙减小，载流子的散射降低，其电输运性能提高。与单层磷烯相比，双层异向磷烯具有更高的热电优值，温度在800 K时在AC方向上N-type双层异向磷烯的热电优值可达2.336。研究结果可为相关热电材料的性能调控提供理论借鉴和参考。

关键词: 纳米材料, 磷烯, 热电优值, 第一性原理, 数值模拟