低维微纳米非线性光学材料的共价/非共价构筑

The low-dimensional micro-/nano- scale materials with highly efficient optical nonlinearity are the key materials for developing all-optical switches and optical computers. Organic nonlinear optical (NLO) materials have their intrinsic merits in high NLO susceptibilities, fast optical responses, as well as easy processing methods, and therefore promise advanced future applications. However, the NLO properties of organic materials are highly dependent on their supramolecular organizations, in particular for second-order NLO a macroscopic dipole and a noncentrosymmetry are necessary. Such a requirement is especially difficult for organic molecules which usually interact with each other by noncovalent weak interactions. It remains a great challenge to translate the molecular hyperpolarizability β to material susceptibility χ(2)..This project intends to propose a universal method for the construction of noncentrosymmetric second-order nonlinear optical materials from diverse NLO dyes, based on the cooperation effects of the cavalent and noncavalent interactions of the helical polyisocyanopeptides. The scaffold of the helical backbone, assisted by the noncovalent hydeogen bondings and π-π stacking, realizes the noncentrosymmtric arrangements of the NLO dyes. 1-D nanowires with second-order NLO properties will be provided by electrospinning of the polymer solutions, while 2-D NLO films will be synthesized by in-situ polymerization of NLO monomers catalyzed by the Ni-immobilized substrates. The relationship between properties and structures of the NLO materials will be correlated to provide guidelines for the future design of subwavelength scale NLO materials.

具有强非线性光学响应的低维微纳米材料是实现全光开关器件、开发光学计算机的最关键材料。有机非线性光学材料具有非线性光学系数高、响应快、易于修饰加工等优点，具有广阔的应用前景。然而有机材料的非线性光学性质依赖于分子的组织结构，尤其是二阶非线性光学需要材料具有宏观偶极距和非中心对称性，这一要求对以非共价弱相互结合的有机分子尤其苛刻，如何实现分子的超极化率β到材料的极化率χ(2)的有效转化仍极具挑战。.本课题旨在发展普适于多种非线性光学材料染料，基于螺旋聚合物共价与非共价协同作用的非线性光学低维微纳米材料的构筑方法。利用聚合物的刚性骨架为平台，结合氢键及π-π堆积等弱相互作用协同实现染料的非中心对称排列；借助静电纺丝技术构建本体二阶非线性光学响应的纳米线，借助基底催化原位聚合构筑二阶非线性光学响应的薄膜材料；探索材料的非线性光学性质与其结构的内在联系，为构筑有机非线性光学低维微纳米材料提供新思路。

具有强非线性光学响应的低维微纳米材料是实现全光开关器件、开发光学计算机的最关键材料。有机非线性光学材料具有非线性光学系数高、响应快、易于修饰加工等优点，具有广阔的应用前景。然而有机材料的非线性光学性质依赖于分子的组织结构，尤其是二阶非线性光学需要材料具有宏观偶极距和非中心对称性，这一要求对以非共价弱相互结合的有机分子尤其苛刻，如何实现分子的超极化率β到材料的极化率χ(2)的有效转化仍极具挑战。.本项目发展了非线性光学微纳米材料的构筑方法学。基于螺旋聚合物与有机共轭分子等构筑基元的共价与非共价协同作用，构筑了一系列具有优异非线性光学性能的低维微纳米材料。研究了聚异腈等螺旋聚合物的组装行为；以芴酮衍生物等有机共轭分子作为构筑基元，制备得到了一系列具有优异非线性光学响应的微纳米结构，探索了它们在太赫兹等非线性光学器件中的应用前景；开拓了有机/无机杂化体系构筑低维非线性光学微纳米材料的方法，以有机非线性光学纳米线与Fabry-Perot光学微腔的相互作用，通过强耦合作用增强杂化体的非线性光学响应；将手性配体引入到钙钛矿构筑基元，得到具有二阶非线性光学响应的手性钙钛矿微纳米材料；研究了扭曲并苯等材料体系的非线性光学特性与其分子结构与超分子组装的内在联系，进一步考察了跃迁偶极矩对于非线性光学性质的重要贡献，系统研究了有机分子材料的非线性光学性质的构效关系，为构筑有机非线性光学低维微纳米材料提供了新的思路。