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

该项目的目标是制备、研究和优化一种新型的杂化材料，该杂化材料由嵌入到功能聚合物的无定形基质中的无机光折变纳米晶体组成。例如，由于整体光伏效应，在光照下纳米晶体中形成了很大的电场。这些场穿透到聚合物主体中，并由于例如二次电光效应而改变折射率，这可以通过极性分子在纳米晶场中的取向来增强。因此，经过优化后，该材料有可能显示出优异的光折变性能。纳米晶体可能会表现出新的物理效应，因为它们的亚波长尺寸特别是由于表面碰撞而产生的。例如，吸收和整体光伏系数可能会受到影响。为了优化光谱响应、记录时间以及引起的折射率变化的幅度和寿命，将研究纳米晶体和聚合物的许多组合。包括完整的实验表征和理论描述(纳米晶体中的效应、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).