Charge-Carrier Dynamics in Novel Photorefractive Inorganic: Organic Nanocomposites

本项目主要研究一类新型无机纳米晶体：聚合物纳米复合材料中与光折变效应相关的基本过程。提出的新一类材料具有前景，因为光折变的光谱响应可以选择性地选择在可见光和近红外通信波长下工作，这一特征主要来自无机系统中的量子限制效应，将允许在低工作电压下观察到光折变效应。这种聚合物材料光敏化的新方法不仅提供了一种可以显著增强光折变效应的特性和过程的方法，而且为研究光电荷产生、迁移、捕获和重组的基本物理过程提供了机会。光电导率实验将用于表征纳米复合材料的光敏性，而迁移率数据将从飞行时间实验中获得。然后使用已建立的模型（如Onsager重组模型）对结果进行分析。光折变特性将使用简并四波混频和非对称双光束耦合技术。这些实验将提供洞察光栅形成的几个方面，如相移和光栅生长和衰减的动力学。迁移率的温度依赖性以及光栅动力学实验将为载流子的捕获和脱陷机制提供额外的见解。新型光学材料的发展可能对技术产生非常重要的影响，并且需要利用无机和有机材料的最佳性能。在这些领域培养的研究生和博士后将有良好的就业前景。

This project focuses on the study of basic processes associated with the photorefractive effect in a novel class of inorganic nanocrystal: polymer nanocomposites. The proposed new class of materials holds promise in that the spectral response for photorefractivity can be selectively chosen for operation at visible as well as near infra-red communication wavelengths, a feature primarily derived from the quantum confinement effect in inorganic systems will allow the photorefractive effect to be observed at low operational voltage. This novel approach to the photosensitization of polymeric materials not only offers a method by which the characteristics and processes involved in the photorefractive effect may be significantly enhanced, but also provides the opportunity to study the fundamental physical processes of photocharge generation, migration, and trapping and recombination. Photoconductivity experiments will be utilized in the characterization of the photosensitivity of the nanocomposite and mobility data will be obtained from time-of-flight experiments. The results will then be analyzed using established model, e.g. the Onsager recombination model. Photorefractive characterizations will be made using degenerate-four-wave-mixing- as well as asymmetric-two beam coupling techniques. These experiments will provide insight into several aspects of grating formation such as phase shift and the kinetics of grating growth and decay. The temerature dependence of the mobility as well as grating kinetic experiments will provide additional insight into the mechanism of trapping and detrapping of carriers.%%%The development of novel optical materials should be reviewed as having potentially a very important impact on technology, and the best properties of both inorganic and organic materials need to be exploited. Graduate and post -doctoral students trained in these areas will have excellent job prospects.