Organic Semiconductor Devices: Contacts, Transport and the Nanoscale Limit

这项研究的目的是了解由有机半导体聚合物制成的具有有源区的场效应晶体管的电子性质的控制过程。特别令人感兴趣的是：从金属电极向聚合物中注入电荷；限制电荷在聚合物中传输的过程；以及纳米结构对两者的影响。该方法使用了三种类型的实验：纳米级晶体管中的电子测量；聚合物发出的太赫兹辐射的测量，作为推断块体中纳米级电荷动力学的手段；以及扫描隧道显微镜技术，用于空间分辨载流子密度和能带能量的确定。这项工作的智力价值在于，这项研究解决了几个关键的未回答的基本问题(例如，有机半导体中电荷传输的最终限制因素是什么？金属-有机界面在电荷转移和能带弯曲方面发生了什么？)和实际的引进(例如，如何优化有机场效应晶体管器件的性能？)更广泛的影响包括对有技术素养的劳动力的研究、培训和教育，以及与新兴技术的强烈相关性，如柔性显示器、可打印电子产品、有机发光二极管和有机光伏。该提案解决的许多相同的器件物理问题对于优化这些技术中的器件设计至关重要。

The objective of this research is to understand the processes that govern the electronic properties of field-effect transistors with active regions made from organic semiconducting polymers. Of particular interest are: the injection of charge from metal electrodes into the polymer; the processes that limit the transport of charge within the polymer; and the effect of nanoscale structure on both. The approach uses three types of experiments: electronic measurements in transistors fabricated on the nanoscale; measurements of terahertz radiation emitted by the polymer as a means of inferring nanoscale charge dynamics in the bulk; and scanning tunneling microscopy techniques for spatially resolved determination of carrier density and band energetics.The intellectual merit of this work is that this research addresses several crucial unanswered questions of both fundamental interest (e.g. What is the ultimate limiting factor in charge transport through organic semiconductors? What happens at the metal-organic interface in terms of charge transfer and band bending?) and practical import (e.g. How can organic field-effect transistor device performance be optimized?). The broader impacts include research training and education of the technically literate workforce, and strong relevance to burgeoning technologies, such as flexible displays, printable electronics, organic light emitting diodes, and organic photovoltaics. Many of the same device physics issues addressed by this proposal are central to optimizing device designs in these technologies.