Controlling the Morphology and Electronic Properties of Conjugated Polymer/Metal Interfaces

该项目解决了聚合物/电极界面的分子水平结构与光电器件性能的关系。当金属蒸发到共轭聚合物上时，碳-碳键可能断裂，金属-碳键可能形成，并且聚合物可能被电掺杂。此外，电荷注入聚合物基器件的方式取决于聚合物/金属界面的化学细节。所追求的方法利用表面特异性非线性光学光谱、二次谐波和频率产生来直接探测共轭聚合物界面的化学结构。光学实验主要研究聚合物/真空界面，将非线性光学信号与显微镜（AFM）研究的形态信息联系起来。进一步的实验将探索金属-碳键的存在和聚合物/金属界面处聚合物的掺杂程度。此外，界面载流子动力学将在操作设备中进行探测，使设备性能与聚合物/金属界面结构的特定变化相关。总体目标是将界面性质和形态与器件性能相关联，以便可以针对所需应用优化界面。该项目解决了与具有技术相关性的电子/光子材料相关的基础研究问题。这一提议的广泛影响是多方面的。拟议的实验将教育学生在本科生，研究生和博士后水平的学科领域的激光，光学，先进的光谱学，纳米尺度的结构测量，半导体物理和光电器件制造。此外，这些教育机会将提供给传统上在物理科学领域代表性不足的学生。由于金属电极对于任何类型的聚合物基设备的操作都是必要的，因此该项目中开发的方法和测量将增强该项目直接关注之外的研究领域。***

This project addresses how molecular-level structure of polymer/electrode interfaces is related to optoelectronic device performance. When a metal is evaporated onto a conjugated polymer, car-bon-carbon bonds may be broken, metal-carbon bonds may be formed, and the polymer may be-come electrically doped. Additionally, the way charge is injected into polymer-based devices is determined by details of the chemistry at polymer/metal interfaces. The approach pursued takes advantage of surface-specific non-linear optical spectroscopies, second harmonic and sum fre-quency generation, to directly probe the chemical structure of conjugated polymer interfaces. Ini-tial experiments focus on polymer/vacuum interfaces, relating non-linear optical signals with morphological information from microscopic (AFM) studies. Additional experiments will ex-plore the existence of metal-carbon bonds and the extent of doping of the polymer at poly-mer/metal interfaces. Additionally, interfacial carrier dynamics will be probed in operating de-vices, allowing device performance to be correlated with specific changes in polymer/metal inter-facial structure. The overall goal is to relate interfacial properties and morphology with device performance, so that the interfaces can be optimized for desired applications. %%% The project addresses fundamental research issues associated with electronic/photonic materials having technological relevance. The broader impacts of this proposal are several-fold. The pro-posed experiments will educate students at the undergraduate, graduate and postdoctoral levels in the subject areas of lasers, optics, advanced spectroscopies, nanometer-scale structural measure-ments, semiconductor physics, and optoelectronic device fabrication. Moreover, these educa-tional opportunities will be provided to students traditionally under-represented in the physical sciences. Because metal electrodes are necessary for the operation of any type of polymer-based device, the methods and measurements developed in this project will enhance areas of research outside the immediate focus of the project. ***