Shift current response in elemental two-dimensional ferroelectrics
Shift current response in elemental two-dimensional ferroelectrics
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DOI：
10.1038/s41524-023-01026-3
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发表时间：
2022-12
影响因子：
9.7
通讯作者：
Z. Qian;Jian Zhou;Hua Wang;Siyi Liu
中科院分区：
文献类型：
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作者：
Z. Qian;Jian Zhou;Hua Wang;Siyi Liu
没有反转对称性的块体材料可以在照明下产生直流电。这种无界面的电流产生机制，称为体光伏效应（BPVE），不依赖于p-n结。在这里，我们探讨了移位电流的产生，一个主要的机制负责BPVE，在单元素的二维（2D）的铁电体所代表的磷烯类单层的As，Sb和Bi。由这些元素2D材料提供的强共价性、小带隙和大的联合态密度产生大的移位电流，优于许多最先进的材料。我们发现，移位电流，由于其拓扑性质，敏感地依赖于布洛赫波函数的细节。在密度泛函理论计算中，考虑广义梯度近似下的电子交换关联势和自旋轨道相互作用是获得可靠的频率依赖位移电流响应的关键。
A bulk material without inversion symmetry can generate a direct current under illumination. This interface-free current generation mechanism, referred to as the bulk photovoltaic effect (BPVE), does not rely onp-njunctions. Here, we explore the shift current generation, a major mechanism responsible for the BPVE, in single-element two-dimensional (2D) ferroelectrics represented by phosphorene-like monolayers of As, Sb, and Bi. The strong covalency, small band gap, and large joint density of states afforded by these elemental 2D materials give rise to large shift currents, outperforming many state-of-the-art materials. We find that the shift current, due to its topological nature, depends sensitively on the details of the Bloch wave functions. It is crucial to consider the electronic exchange-correlation potential beyond the generalized gradient approximation as well as the spin-orbit interaction in density functional theory calculations to obtain reliable frequency-dependent shift current responses.