论文标题
强大的光伏效应和二维硒中的第二次谐波产生
Strong bulk photovoltaic effect and second-harmonic generation in two-dimensional selenium and tellurium
论文作者
论文摘要
最近已经准备好了很少的硒和柜膜，它们提供了一个新的平台来探索二维（2D）元素材料的新型特性。 In this work, we have performed a systematic first-principles study on the electronic, linear, and nonlinear optical (NLO) properties of atomically thin selenium and tellurium films within the density-functional theory with the generalized gradient approximation plus scissors correction using the band gaps from the relativistic hybrid Heyd-Scuseria-Ernzerhof functional calculations.有趣的是，我们发现很少的SE和TE具有大型的第二谐波产生（SHG），线性电效应和散装光伏效应。特别是，Trilayer（TL）TE具有较大的SHG系数，比广泛使用的NLO材料Gan大的65倍以上。 BiLayer（BL）TE具有巨大的静态SHG系数，比GAN大100倍以上。此外，单层（ML）SE具有较大的SHG系数。此外，我们预测TL TE表现出强大的散装光伏效应（BPVE），大于GES，GES是迄今为止BPVE最大的极性系统。尽管散装和2D SE的偏移电流电导率是可比的，但TL TE的移位电流电导率的率是散装TE的五倍。最后，对计算出的电子带结构的分析表明，2D SE和TE材料的强NLO响应主要来自其低维度结构，具有高各向异性，方向共价键，孤对电子和相对较小的带隙。这些发现为寻找出色的NLO和BPVE材料提供了实用的策略。
Few-layer selenium and tellurium films have been recently prepared, and they provide a new platform to explore novel properties of two-dimensional (2D) elemental materials. In this work, we have performed a systematic first-principles study on the electronic, linear, and nonlinear optical (NLO) properties of atomically thin selenium and tellurium films within the density-functional theory with the generalized gradient approximation plus scissors correction using the band gaps from the relativistic hybrid Heyd-Scuseria-Ernzerhof functional calculations. Interestingly, we find that few-layer Se and Te possess large second-harmonic generation (SHG), linear electro-optic effect, and bulk photovoltaic effect. In particular, trilayer (TL) Te possesses large SHG coefficient, being more than 65 times larger than that of GaN, a widely used NLO material. Bilayer (BL) Te has huge static SHG coefficient, being more than 100 times larger than that of GaN. Furthermore, monolayer (ML) Se possesses large SHG coefficient. Moreover, we predict that TL Te exhibits strong bulk photovoltaic effect (BPVE), being greater than that of GeS, a polar system with the largest BPVE found so far. Although the shift current conductivities of bulk and 2D Se are comparable, the shift current conductivities of TL Te are five times larger than those of bulk Te. Finally, an analysis of the calculated electronic band structures indicates that the strong NLO responses of 2D Se and Te materials are primarily derived from their low-dimensional structures with high anisotropy, directional covalent bonding, lone-pair electrons, and relatively small band gaps. These findings provide a practical strategy to search for excellent NLO and BPVE materials.
