Optimizing Conjugated Polymer Films for Desired Applications: Controlling Interchain, Interfacial and Intensity-Dependent Interactions

9971842 Schwartz这项研究描述了一系列实验，旨在提高我们在三个方面对共轭聚合物的理解，这三个领域是在实际设备中最大限度地开发这些材料的潜力的关键：确定聚合物链之间的相互作用的作用，了解聚合物激发态之间的相互作用，以及探索金属/聚合物界面的化学性质。首先，通过用不同的溶剂浇注共轭聚合物薄膜和/或进行热处理来改变链间相互作用。对这些样品的超快激光研究将监测单链激发态(通过它们的发射)和链间激发态(通过它们的吸收)之间的关系，并将这种关系与X射线衍射和/或原子力显微镜确定的链的堆积方式相关联。还将研究封装在多孔二氧化硅玻璃的纳米级通道中的孤立和排列的高分子链。其次，在监测激发态吸收和受激发射的时间演化的同时，系统地改变激发几何结构的实验将提供关于共轭聚合物中激发态之间相互作用的信息。最后，表面特定的非线性光学光谱，如二次谐波和和频，将直接探测聚合物/金属界面的化学结构，结果将与实际的基于聚合物的光电子器件(如发光二极管)中此类界面的行为相关联。由于共轭聚合物的性质是塑料半导体，因此可以用它们来制造光电子器件。与传统的无机半导体不同，共轭聚合物重量轻、柔性好，可以很容易地制造成所需的形状，并且可以合成在可见光光谱的任何区域都有带隙。与目前在LED、显示器和社会上广泛使用的其他应用中使用的技术相比，共轭聚合物的易加工性和所需的机械性能提供了巨大的优势。例如，共轭聚合物允许构建大面积、灵活的发光面板，并且可以通过喷墨打印直接生产多色显示器。这项拟议的工作旨在学习如何优化这些材料，以满足商业设备或显示器的预期应用。所提出的实验结果应该为控制高分子链之间的相互作用以增强所需的电学或光学性能提供处方；对高强度激发的理解可能为生产塑料半导体激光器打开可能性；从实验中获得的聚合物/电极界面的详细知识可以直接导致器件性能的改进。

9971842SchwartzThis research describes a series of experiments designed to improve our understanding of conjugated polymers in three areas which are key to exploiting these materials to their maximum potential in practical devices: determining the role of interactions between polymer chains, understanding the interactions between polymer excited states, and exploring the chemical nature of the metal/polymer interface. First, interchain interactions will be varied by casting conjugated polymer films from different solvents and/or annealing. Ultrafast laser studies on these samples will monitor the relationship between single-chain excited states (through their emission) and interchain excited states (through their absorption), and will correlate this relationship with how the chains are packed as established by X-ray diffraction and/or atomic force microscopy. Isolated and aligned polymer chains encapsulated in the nanoscale channels of a porous silica glass will also be studied. Second, experiments that systematically vary both the excitation geometry while monitoring the time evolution of the excited state absorption and stimulated emission will provide information about the interactions between excited states in conjugated polymers. Finally, surface-specific non-linear optical spectroscopies such as second harmonic and sum frequency generation will directly probe the chemical structure of the polymer/metal interface, and the results will be correlated with the behavior of such interfaces in practical polymer-based optoelectronic devices such as light-emitting diodes.Optoelectronic devices can be created from conjugated polymers due to their nature as plastic semiconductors. Unlike conventional inorganic semiconductors, conjugated polymers are lightweight and flexible, can be easily fabricated into desired shapes, and can be synthesized to have band gaps in any region of the visible spectrum. The ease of processing and desirable mechanical properties of conjugated polymers offer enormous advantages compared to the technologies presently used in LED's, displays, and other applications that are widespread in society. For example, conjugated polymers allow the construction of large-area, flexible light-emitting panels, and multi-color displays can be produced directly by ink-jet printing. The proposed work is aimed at learning how to optimize these materials for desired applications in commercial devices or displays. The results of the proposed experiments should provide a prescription for controlling the interactions between polymer chains to enhance desired electrical or optical properties; the understanding of excitations at high intensity may open the possibility for producing plastic diode laser; and the detailed knowledge of the polymer/electrode interface obtained from the experiments could lead directly to improvements in device performance.