Sb nanosheets, also known as antimonene, have received ever-growing consideration as a promising new type of two-dimensional (2D) material due to their many attractive properties. However, how their nonlinear optical (NLO) properties are affected by their nanosheet structure and measurement conditions remains unclear. Herein, we report a successful size-selective production method for Sb nanosheets, which is based on a combination of lithium ion intercalation, solvent exfoliation and size selection centrifugation. This high-yield and size-selective preparation method enables fundamental investigation on the relation of the intrinsic optical properties of Sb nanosheets. Nanosecond Z-scan measurements revealed a unique size-dependent broadband NLO response. When the average size is reduced from 3 micrometers to 50 nanometers, the Sb nanosheets exhibit a clear transition from saturable absorption to reversed saturable absorption. Ultrafast transient absorption spectroscopic investigation indicated that exciton cooling is significantly faster in a small nanosheet than in large ones, revealing that the different exciton relaxation dynamic plays key roles in the distinct size-tunable nonlinear optical response. This work paves new ways towards the mass production and practical application of antimonene.

中文翻译：

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二维锑纳米片的可调非线性光学响应和载流子动力学。

锑纳米片，也称为锑，由于其许多吸引人的特性，已成为一种有希望的新型二维（2D）材料，受到越来越多的关注。但是，尚不清楚它们的非线性光学（NLO）特性如何受到其纳米片结构和测量条件的影响。本文中，我们报告了一种成功的Sb纳米片尺寸选择生产方法，该方法基于锂离子嵌入，溶剂剥离和尺寸选择离心的组合。这种高产率和尺寸选择性的制备方法能够对Sb纳米片的固有光学性质之间的关系进行基础研究。纳秒Z扫描测量显示出独特的，与尺寸有关的宽带NLO响应。当平均尺寸从3微米减小到50纳米时，Sb纳米片表现出从饱和吸收到反向饱和吸收的清晰过渡。超快速瞬态吸收光谱研究表明，小纳米片中的激子冷却明显快于大纳米片，这表明不同的激子弛豫动力学在不同的尺寸可调非线性光学响应中起关键作用。这项工作为大规模生产和实际应用锑法开辟了新途径。