Photorefractive Hybrid Materials Based on Inorganic Nano-Crystals Embedded in an Amorphous Organic Host

该项目的目标是制造、研究和优化一种新型的混合材料，这种材料由无机光折变纳米晶体嵌入到功能聚合物的无定形基质中。在光照下，纳米晶体中会形成较大的电场，这是因为，例如，大块光伏效应。由于二次电光效应等原因，这些电场穿透聚合物基体并改变折射率，而这种效应可以通过纳米晶体场中极性分子的取向来增强。因此，经过优化后的材料具有显示优越光折变特性的潜力。纳米晶体可能由于其亚波长尺寸而表现出新的物理效应，特别是由于表面撞击。例如，吸收和体积光伏系数会受到影响。为了优化光谱响应，记录时间以及诱导指数变化的幅度和寿命，将研究纳米晶体和聚合物的许多组合。完整的实验表征和理论描述是有针对性的（纳米晶体的效应，纳米晶体与聚合物的相互作用，光散射，整体光敏性和光学非线性）。

The goal of the project is to fabricate, to investigate, and to optimise a new class of hybrid materials consisting of inorganic photorefractive nano-crystals embedded into an amorphous matrix of a functional polymer. Large electric fields build up in nano-crystals under illumination because of, e.g., the bulk photovoltaic effect. These fields penetrate into the polymer host and change the refractive index owing to, e.g., the quadratic electro-optic effect, which can be enhanced by orientation of polar molecules in the nano-crystal fields. Thus after optimisation the material has the potential to show superior photorefractive properties. Nano-crystals may exhibit new physical effects owing to their sub-wavelength dimensions that result especially from surface impacts. E.g. absorption and the bulk photovoltaic coefficient can be affected. For optimisation of spectral response, recording time as well as magnitude and life-time of the induced index changes, many combinations of nano-crystals and polymers will be studied. Full experimental characterisations and theoretical desriptions are targeted (effects in nano-crystals, interaction of nano-crystals with polymers, light scattering, overall photosensitivity and optical nonlinearities).