结构导向单金属内嵌富勒烯单晶材料的非线性光学特性研究

Fullerene has wide application potential in fields like all-optical switches, optical communication due to its large second order and third order non-linear polarizability and fast non-linear optical response as a result of the delocalized π electrons. The endohedral fullerenes have much higher non-linear optical response than empty fullerenes due to the charge transfer from endohedral atom or cluster to cage. Compared to isotropic solution, anisotropic single crystal is more polarized under light and has higher density of π electron which makes it promising non-linear optical material with outstanding performance. In this project, we will study the non-linear optical properties of structure-oriented monometallofullerene crystals. Endohedral fullerene crystal with macroscopic high second order polarizability will be obtained by optimizing fullerene arrangement with quantum chemistry calculation method. The third order optical property will be characterized by ultrashort femtosecond laser pulse. The effect of carbon cage and endohedral atom on non-linear optical properties will be investigated. The effect of material micro-structure, electronic properties, surface defects on non-linear optical properties will be studied basing the fabrication and characterization of fullerene single crystal thin-film, which will provide theoretical and experimental support for the development of new non-linear optical material.

π电子离域的富勒烯材料因具有大的二阶和三阶非线性极化率和较快的非线性光学响应，在全光开关、光通讯等领域有广阔的应用前景。由于内嵌原子（团簇）向碳笼的电荷转移，内嵌富勒烯的非线性光学响应明显高于空心富勒烯。与各向同性的溶液状态相比，各向异性的单晶结构与光波作用时产生更大极化，且单晶态内嵌富勒烯π电子云密度更高，有望成为性能突出的非线性光学材料。本项目拟开展结构为导向的单金属内嵌富勒烯单晶材料非线性光学特性研究。通过量子化学计算，优化富勒烯分子在单晶中的排列方式，发展内嵌富勒烯单晶制备方法，获得宏观二阶极化率高的内嵌富勒烯单晶材料。利用超短脉冲的飞秒激光研究其三阶非线性光学特性。讨论不同碳笼、内嵌原子对非线性光学性质的影响；制备内嵌富勒烯单晶薄膜，揭示溶液、单晶与单晶薄膜非线性光学效应与材料微结构、电子特性、表面缺陷之间的关系，为新型非线性光学材料的发展提供理论基础和实验依据。

π电子离域的富勒烯材料因具有大的二阶和三阶非线性极化率和较快的非线性光学响应，在全光开关、光通讯等领域有广阔的应用前景。本项目采用了B3LYP 方法对富勒烯单晶进行优化，通过 TDDFT 方法分析了富勒烯单晶各部分电荷分布和电子跃迁性质，理解内嵌富勒烯单晶非线性光学性质的起源。在理论指导下，选取了合适的溶剂分子，优化了富勒烯分子在单晶中的排列方式，制备了不同结构的富勒烯单晶材料，获得了宏观二阶极化率高的富勒烯单晶材料。并且发展了一种单晶富勒烯近红外柔性发光薄膜的制备方法。主要完成研究内容如下：1）制备了富勒烯晶体羧甲基纤维素钠复合膜并研究了其非线性光学效应；2）制备了柔性富勒烯立方晶体薄膜并研究了其聚集诱导近红外发光效应；3）制备了富勒烯六方棒状晶体/海藻酸钠复合柔性薄膜并研究了协同发光效应。