Manipulating Peierls Distortion in van der Waals NbOX2 Maximizes Second-Harmonic Generation.
Manipulating Peierls Distortion in van der Waals NbOX2 Maximizes Second-Harmonic Generation.
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DOI：
10.1021/jacs.3c04971
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发表时间：
2023-07
影响因子：
15
通讯作者：
Tonghuan Fu;Kejun Bu;Xuzhou Sun;Dong Wang;Xin Feng;Songhao Guo;Zongdong Sun;Yuqiang Fang;Qingyang Hu;Yang Ding;T. Zhai;Fuqiang Huang;X. Lü
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作者：
Tonghuan Fu;Kejun Bu;Xuzhou Sun;Dong Wang;Xin Feng;Songhao Guo;Zongdong Sun;Yuqiang Fang;Qingyang Hu;Yang Ding;T. Zhai;Fuqiang Huang;X. Lü
二维（2D）货车德瓦尔斯（vdW）材料具有宽松的相位匹配条件和高度可调的光学非线性，赋予它们在纳米级非线性光学（NLO）器件中的潜在应用。尽管取得了重大进展，但2D NLO材料的基本问题仍然存在，例如结构畸变如何影响二阶NLO特性，这需要先进的监管和原位诊断工具。在这里，通过施加压力，以不断调整的位移的Nb原子在2D vdW NbOI 2，我们有效地调制的极化，并实现了3倍的二次谐波产生（SHG）在2.5 GPa的提升。通过引入Peierls畸变参数λ，建立了λ与倍频强度之间的定量关系。重要的是，我们进一步证明了在环境条件下，通过阴离子取代来调节NbO（I1-xBrx）2（x = 0-1）化合物的畸变，可以实现SHG增强，其中化学剪裁模拟了压力对结构优化的影响。因此，NbO（I0.60Br0.40）2（λ = 0.17）表现出比单层WSe 2高2个数量级的巨大二次谐波，达到了已报道的二维vdW非线性光学材料中的最高值。这项工作明确地证明了Peierls畸变和SHG性质之间的相关性，更广泛地说，通过操纵结构畸变为先进的NLO材料的发展开辟了新的途径。
Two-dimensional (2D) van der Waals (vdW) materials, featuring relaxed phase-matching conditions and highly tunable optical nonlinearity, endow them with potential applications in nanoscale nonlinear optical (NLO) devices. Despite significant progress, fundamental questions in 2D NLO materials remain, such as how structural distortion affects second-order NLO properties, which call for advanced regulation and in situ diagnostic tools. Here, by applying pressure to continuously tune the displacement of Nb atoms in 2D vdW NbOI2, we effectively modulate the polarization and achieve a 3-fold boost of the second-harmonic generation (SHG) at 2.5 GPa. By introducing a Peierls distortion parameter, λ, we establish a quantitative relationship between λ and SHG intensity. Importantly, we further demonstrate that the SHG enhancement can be achieved under ambient conditions by anionic substitution to tune the distortion in NbO(I1-xBrx)2 (x = 0-1) compounds, where the chemical tailoring simulates the pressure effects on the structural optimization. Consequently, NbO(I0.60Br0.40)2 with λ = 0.17 exhibits a giant SHG of over 2 orders of magnitude higher than that in monolayer WSe2, reaching the record-high value among reported 2D vdW NLO materials. This work unambiguously demonstrates the correlation between Peierls distortion and SHG property and, more broadly, opens new paths for the development of advanced NLO materials by manipulating the structure distortions.