CAREER: Understanding the Growth Mechanisms and Properties of Metal Nanowires

技术总结这份由固态和材料化学计划发起的职业计划的目标是阐明金属纳米线在溶液中生长的过程，利用这一理解来改进对金属纳米线尺寸的综合控制，并在实际应用的背景下研究金属纳米线的结构-性能关系。纳米线的成核和生长将用暗场光学显微镜和过渡电子显微镜实时可视化。可视化获得的动力学数据将是解决有关纳米线生长的几个悬而未决的问题的有力工具，包括：(1)添加到纳米线中的物种是由金属离子、还原的金属原子还是金属团簇组成？(2)限制纳米线生长速度的化学步骤是什么？(3)封顶剂如何改变纳米线的生长动力学和纳米线的形态？更深入地了解封端剂的作用将有助于发现一种新的封顶剂，使纳米线的生产能够在更广泛的维度上进行。测量与温度相关的成核速率将有助于通过设计反应的温度分布来及时分离纳米线的成核和生长，从而允许生产具有精确定义的长度和直径的纳米线。从合成研究中获得的定义明确的纳米线将被用作在透明、导电薄膜和光学偏振器的背景下理解纳米线的结构-性质关系的平台。非技术SUMMARY金属纳米线看起来像松针，但小一万倍，有可能降低成本，提高触摸屏、太阳能电池、有机LED、平板显示器、电致变色窗口、增强现实显示器、飞机雷击保护、电池电极、传感器、催化剂和可穿戴电子设备的性能。目前，人们对纳米线在液体中自发生长的过程知之甚少，这限制了开发更好的方法来控制纳米线的尺寸，以便在实际应用中了解和优化其性能。这项职业计划由固态和材料化学计划赞助，描述了一项综合研究和教育计划，致力于发现纳米线生长的原因，利用这些信息在广泛的维度上以前所未有的精度生长纳米线，在与学术和工业合作伙伴的应用背景下研究这些结构的特性，并通过旨在改善未被充分代表的群体参与的外联计划向公众传播这些结果。研究方法将侧重于开发技术，使研究人员能够实时观察原子组装成纳米线的过程。这项基础性研究的目标包括发现(1)纳米线形成的过程，(2)影响纳米线尺寸的因素，以及(3)如何在更大的尺寸范围内更精确地控制纳米线的尺寸。然后，将在太阳能电池和增强现实眼镜的隐形眼镜中表征纳米线的结构依赖属性。该项目产生的新发现将被整合到非裔美国高中生与研究生导师合作的实践活动中，并通过科学博览会、课堂演示、博物馆展品和在线视频向更广泛的公众展示。

TECHNICAL SUMMARYThe objectives of this CAREER proposal, sponsored by the Solid State and Materials Chemistry program, are to clarify the processes by which metal nanowires grow in solution, use this understanding to improve synthetic control over metal nanowire dimensions, and study the structure-property relationship of metal nanowires in the context of practical applications. Nanowire nucleation and growth will be visualized in real-time with dark-field optical microscopy and transition electron microscopy. The kinetic data obtained from visualization will be a powerful tool for addressing several unanswered questions about nanowire growth, including: (1) Does the species adding to the nanowire consist of metal ions, reduced metal atoms, or metal clusters? (2) What is the chemical step that limits the rate of nanowire growth? (3) How does the capping agent alter nanowire growth kinetics and nanowire morphology? A deeper understanding of the role of the capping agent will facilitate the discovery a new capping agents that enable the production of nanowires across a broader range of dimensions. Measurement of the temperature-dependent nucleation rate will facilitate the separation of nanowire nucleation from nanowire growth in time by engineering the temperature profile of the reaction, and thus allow for the production of nanowires with precisely defined lengths and diameters. The well-defined nanowires obtained from synthetic studies will be used as a platform for understanding the structure-property relationships of nanowires in the context of a transparent, conducting film, and an optical polarizer. NON TECHNICAL SUMMARYMetal nanowires, which look similar to pine needles but are 10,000 times smaller, have the potential to reduce the cost and improve the performance of touch screens, solar cells, organic LEDs, flat-panel displays, electrochromic windows, augmented reality displays, lightning strike protection for aircraft, battery electrodes, sensors, catalysts, and wearable electronics. At present, the processes by which nanowires spontaneously grow in liquids are poorly understood, and this is limiting the development of better ways to control the dimensions of nanowires so as to understand and optimize their properties in practical applications. This CAREER proposal, sponsored by the Solid State and Materials Chemistry program, describes an integrated research and educational plan dedicated to discovering why nanowires grow, using this information to grow nanowires with unprecedented precision over a wide range of dimensions, studying the properties of these structures in the context of applications with academic and industrial partners, and disseminating these results to the public though an outreach program that aims to improve participation of underrepresented groups. The research approach will focus on the development of techniques that allow researchers to watch, in real-time, the assembly of atoms into nanowires. Goals of this fundamental study include finding (1) the processes by which nanowires form, (2) the factors that influence the dimensions of a nanowire, and (3) how to control the dimensions of nanowires with greater precision over a greater range of sizes. The structure-dependent properties of nanowires will then be characterized in solar cells, and in contact lenses for augmented reality glasses. The new discoveries generated by this program will be integrated into hands-on activities by African American high-school students working with graduate student mentors, and presented to the broader public through science fairs, classroom demonstrations, museum exhibits and online videos.