Scanned-Probe Characterization of Charge Trapping and Fluctuations in Organic Semiconductors

有机半导体中电荷捕获和波动的扫描探针表征

• 批准号: 1006633
• 负责人: John Marohn
• 金额: $ 39万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1006633&HistoricalAwards=false
• 关键词: Scanned; Probe; Characterization; Charge; Trapping

TECHNICAL SUMMARY:A microscopic understanding of the mechanisms of charge trapping, transport, injection, and charge generation in organic semiconductors is presently lacking. The development of organic circuits and solar cells could be greatly accelerated if a better basic understanding of these fundamental processes were available. Improving our basic understanding of fundamental processes in organic semiconductor devices is challenging. Nearly all organic semiconductor devices show significant device-to-device variation, and the most promising devices are often comprised of complex multicomponent blends. To build up a microscopic picture of charge trapping and transport in organic semiconductors, we will study organic devices in situ using vacuum, variable-temperature electric force microscopy. We will use light-enhanced electric force microscopy as a tool to spectroscopically identify impurities, study charge generation, and probe trapping mechanisms in a wide range of organic semiconductors. In a second set of experiments, a high-compliance silicon microcantilever will be used to measure minute electric field gradient fluctuations near the surface of an organic semiconductor. From these electric field fluctuations we propose to deduce (and image) the diffusion constant of charges beneath the cantilever tip. We expect these microscopic studies will open up exciting possibilities for advancing our understanding of charge generation, transport, trapping, and injection in organic semiconductor materials and devices. This project will train graduate students in the arts of advanced scanned probe microscopy and nanofabrication. These students will broaden their training by working on collaborative projects with scientists at academic, federal, and industrial laboratories. This work is funded by the Solid State and Materials Chemistry program.NON-TECHNICAL SUMMARY:In order for our nation to obtain energy independence, we must be able to manufacture solar cells that can convert sunlight efficiently into electricity. Many materials are being examined for use in solar cells, and none work as well as we need. One promising class of materials is semiconducting polymers, plastics that have the remarkable property of being able to both absorb light and conduct electricity. In order to get these materials to work well in solar cells, the materials need to absorb light, the absorbed light must be converted into an electrical current, and the current must be carried through the material and extracted into a wire. These last two processes - the conversion of light to current and the transport of charge - are not well understood in these materials. Without a better understanding of these processes, it is not clear how to manufacture improved solar cells from semiconducting polymers. Characterizing these materials is challenging, because their properties show large variations across distances separated by only 10 billionths to 100 billionths of a meter - distances hundreds to thousands of atoms across. To advance our understanding of semiconducting polymers, we will develop new kinds of microscopes that can take pictures of both moving and stationary charges at this length scale in working solar cells. This work will promote the general welfare by training PhD and undergraduate students to do research in energy-related materials and nanotechnology. This work will involve collaboration and knowledge sharing among multiple universities, government laboratories, and industrial laboratories. This work is funded by the Solid State and Materials Chemistry program of the U.S. National Science Foundation.

技术摘要：目前缺乏有机半导体中电荷捕获，运输，注射和电荷产生机制的微观理解。 如果有更好的基本理解，对这些基本过程有更好的基本了解，则可以大大加速有机电路和太阳能电池的发展。 提高我们对有机半导体设备中基本过程的基本理解具有挑战性。 几乎所有有机半导体设备都显示出显着的设备对设备变化，最有前途的设备通常由复杂的多组分混合物组成。 为了建立有机半导体中电荷捕获和运输的微观图片，我们将使用真空，温度的电力显微镜在原位研究有机设备。 我们将使用光增强的电力显微镜作为一种工具，以识别各种有机半导体的杂质，研究电荷产生和探针捕获机制。 在第二组实验中，将使用高规模的硅微型管理器来测量有机半导体表面附近的分钟电场梯度波动。 从这些电场波动中，我们建议推断（和图像）悬臂尖端下电荷的扩散常数。 我们预计这些微观研究将为有机半导体材料和设备中的电荷产生，运输，捕获和注入的理解提供令人兴奋的可能性。 该项目将培训高级扫描探针显微镜和纳米制作艺术的研究生。 这些学生将通过与学术，联邦和工业实验室的科学家进行合作项目来扩大培训。 这项工作由固态和材料化学计划资助。没有技术摘要：为了使我们的国家获得能源独立性，我们必须能够生产可以有效地将阳光转化为电力的太阳能电池。 正在检查许多材料以用于太阳能电池中，而没有什么作用。 一种有希望的材料类是半导体聚合物，塑料具有能够吸收光和传导电力的显着特性。 为了使这些材料在太阳能电池中正常工作，需要吸收光，必须将吸收的光转换为电流，并且必须通过材料将电流携带并提取到电线中。 这些材料中的最后两个过程 - 光转换为电流和电荷的传输 - 尚未很好地理解。 在没有更好地了解这些过程的情况下，尚不清楚如何从半导体聚合物中生产改进的太阳能电池。 表征这些材料是具有挑战性的，因为它们的性质在距离之间显示出较大的变化，只有100亿至100亿米的距离 - 距离数百至数千原子。 为了促进我们对半导体聚合物的理解，我们将开发新型的显微镜，这些显微镜可以在工作太阳能电池中以这种长度尺度拍摄移动和固定电荷的照片。 这项工作将通过培训博士学位和本科生来促进一般福利，从而在能源相关的材料和纳米技术方面进行研究。 这项工作将涉及多个大学，政府实验室和工业实验室之间的合作和知识共享。 这项工作由美国国家科学基金会的固态和材料化学计划资助。