Size-Dependent Nonlinear Optical Properties of Atomically Thin Transition Metal Dichalcogenide Nanosheets
Size-Dependent Nonlinear Optical Properties of Atomically Thin Transition Metal Dichalcogenide Nanosheets
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DOI：
10.1002/smll.201400541
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发表时间：
2015-02-11
期刊：
影响因子：
13.3
通讯作者：
Zhang, Hao-Li
中科院分区：
文献类型：
--
作者：
Zhou, Kai-Ge;Zhao, Min;Zhang, Hao-Li
报道了无修饰的过渡金属二硫属化物（TMD）纳米片的尺寸依赖性非线性光学性质，包括MoS 2，WS 2和NbSe 2。首先，证明了梯度离心法将TMD纳米片分离成不同尺寸。成功的尺寸分离允许第一次研究纳米TMD材料的尺寸依赖性非线性光学性质。Z-扫描测量表明，50-60 nm厚的MoS 2和WS 2纳米片的分散导致反饱和吸收（RSA），这与在较厚样品中看到的饱和吸收（SA）形成对比。此外，NbSe 2纳米片由于其金属性质而没有显示出尺寸依赖性效应。通过瞬态透射光谱测量揭示了该纳米片的尺寸依赖性非线性光学性质背后的机制。
Size-dependent nonlinear optical properties of modification-free transition metal dichalcogenide (TMD) nanosheets are reported, including MoS2, WS2, and NbSe2. Firstly, a gradient centrifugation method is demonstrated to separate the TMD nanosheets into different sizes. The successful size separation allows the study of size-dependent nonlinear optical properties of nanoscale TMD materials for the first time. Z-scan measurements indicate that the dispersion of MoS2 and WS2 nanosheets that are 50-60 nm thick leads to reverse saturable absorption (RSA), which is in contrast to the saturable absorption (SA) seen in the thicker samples. Moreover, the NbSe2 nanosheets show no size-dependent effects because of their metallic nature. The mechanism behind the size-dependent nonlinear optical properties of the semiconductive TMD nanosheets is revealed by transient transmission spectra measurements.