Real-Time Studies of Solution-Processed Organic Semiconductor Thin Films

技术说明：该研究项目的目标是详细了解和控制分子自组织过程，利用简单的薄膜沉积仪器，“空心笔书写器”，从溶液中沉积10 - 100纳米的小分子有机半导体薄膜。中空笔式书写器提供了对有机半导体薄膜性质的令人惊讶的控制程度，在某些方面远远超过了用常规气相沉积可获得的结果。研究小组利用这种方法来研究工艺参数与薄膜性能之间的关系，例如晶粒结构和晶界密度。这些研究的特点是实时分析技术，如光学视频显微镜和同步加速器X射线衍射，这是必要的，以遵循从毫秒到分钟的时间尺度上的结晶过程，并监测和区分分子的短程秩序与长程秩序。此外，还研究了有机场效应晶体管等测试器件中的电荷载流子输运与晶粒结构、内建应力或外加应力的关系。非技术性说明：有机半导体是在分子水平上设计的，具有有用的特性，有望实现新一代的电子电路和太阳能电池。这项研究活动解决了有机电子材料最佳利用的关键步骤，通过可控过程将单个分子组织成晶体形式，例如从液体溶液涂覆成薄层。分子在晶体中的堆积以及晶界结构深刻地影响着薄膜的性质。该研究小组试图了解溶液加工的内在机制，以评估，理解，开发和预测以不断增长的速度合成的新功能材料的潜力。研究的社会影响通过创新的教学方法和追求社区外展目标得到放大，包括：一个本科教学实验室，使有机太阳能电池，通过在线工具进行分析和讨论结果;讲座和演示，旨在让公众参与讨论能源，光，材料和纳米材料的科学和应用。

Technical Description: The goal of this research project is to understand in detail and to control molecular self-organization processes, utilizing a simple thin film deposition instrument, the "hollow pen writer," for depositing 10 - 100 nanometer thin films of small-molecule organic semiconductors from solution. The hollow pen writer provides a surprising degree of control over the properties of organic semiconductor thin films, in some ways far surpassing the results obtainable with conventional vapor deposition. The research team utilizes this method to study the relationships between process parameters and film properties, such as crystalline grain structure and grain boundary density. These studies feature real-time analysis techniques such as optical video microscopy and synchrotron x-ray diffraction, which are necessary in order to follow crystallization processes on time scales from milliseconds to minutes and to monitor and distinguish molecular short-range order versus long-range order. In addition, charge carrier transport in test devices such as organic field effect transistors are studied as a function of grain structure and built-in or applied stress.Non-Technical Description: Organic semiconductors are designed at the molecular level to exhibit useful properties, and they promise the realization of a new generation of electronic circuits and solar cells. This research activity addresses a key step in optimal utilization of organic electronic materials, the organization of individual molecules into crystalline form through controllable processes such as coating from a liquid solution into a thin layer. Packing of molecules into crystals as well as the structure of crystal boundaries profoundly affects the properties of thin films. The research team seeks to understand the mechanisms inherent to solution processing in order to evaluate, understand, exploit, and predict the potential of new functional materials that are being synthesized at an ever-increasing rate. The societal impact of the research is amplified by innovative teaching methods and by pursuing community outreach objectives, including: an undergraduate teaching lab to make organic solar cells, enhanced through online tools for analyzing and discussing results; lectures and demonstrations designed to engage the public in a discussion of the science and applications of energy, light, materials, and nano-materials.