Zhang Shengzi, Kang Lei, Lin Zheshuai
Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Nanoscale. 2020 Jul 21;12(27):14895-14902. doi: 10.1039/d0nr03778h. Epub 2020 Jul 8.
We propose a series of novel ASnX (A = Na, H; X = N, P) layered structures based on first-principles modeling and simulation. These nanosheet materials are all derived from the rational design for the parent structures of NaSnX (X = N, P) with unique divalent tin lone electron pairs. First-principles calculations show that the polar divalent tin effect can lead to strong second-order nonlinear optical (NLO) and large birefringence response in bulk materials, and can also greatly enhance the second harmonic generation (SHG) effect in the corresponding two-dimensional (2D) nanostructures by hydrogen passivation or strain engineering. The correlation between structural evolution and bandgap is illustrated through detailed analysis of the electronic structure and charge transfer model. The SHG effect and its origin can be further evaluated based on the SHG-weighted density scheme, which will facilitate the NLO research of 2D materials in the nitride and phosphide systems.
我们基于第一性原理建模与模拟提出了一系列新型的ASnX（A = Na，H；X = N，P）层状结构。这些纳米片材料均源自对具有独特二价锡孤电子对的NaSnX（X = N，P）母体结构的合理设计。第一性原理计算表明，极性二价锡效应可导致块状材料中产生强烈的二阶非线性光学（NLO）和大双折射响应，并且通过氢钝化或应变工程还可极大地增强相应二维（2D）纳米结构中的二次谐波产生（SHG）效应。通过对电子结构和电荷转移模型的详细分析，阐明了结构演化与带隙之间的相关性。基于SHG加权密度方案可进一步评估SHG效应及其起源，这将有助于氮化物和磷化物体系中二维材料的NLO研究。
