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

该项目的目标是制造，调查和优化一类新的混合材料，由嵌入功能聚合物的无定形基质中的无机光折变纳米晶体组成。在照射下，纳米晶体中会产生大的电场，体光伏效应。这些场渗透到聚合物主体中并改变折射率，二次电光效应，通过极性分子在纳米晶场中的取向可以增强这种电光效应。因此，优化后的材料有可能显示出上级光折射性能。纳米晶体由于其亚波长的尺寸，特别是由于表面撞击，可能会表现出新的物理效应。例如，吸收和体光伏系数可能受到影响。为了优化光谱响应、记录时间以及诱导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。完整的实验表征和理论描述是有针对性的（纳米晶体的影响，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).