Continuous, Large-scale Manufacturing of Functionalized Silver Nanowire Transparent Conducting Films

本研究旨在探索一种经济制备纳米物联网用银纳米线透明导电膜的新技术。纳米物联网有望连接新一代传感器、传感器、数据处理器和通信设备，实现智能互联世界。所有纳米器件的重要组成部分是透明导电膜，通常由银纳米线制成。目前，银纳米线的生产涉及多步骤的批量生产，成本很高。该奖项研究了一种大规模制造银纳米线的新方法，该方法与用于透明导电薄膜图案的三维印刷系统直接耦合。透明导电薄膜和按需印刷银纳米线的成本降低，加速了纳米物联网设备的采用，为美国经济和繁荣做出了贡献。这项研究结合了制造、材料科学、纳米技术、化学和工程等方面。学生积极参与研究，从而获得先进制造业的工程专业知识，这对美国工业很重要。鼓励本科生和研究生，特别是来自代表性不足群体的学生参与研究和培训。本项目研究了在连续反应器中生产基于银纳米线（AgNW）的导电油墨的反应条件和机制，这种导电油墨可以连续印刷到柔性基板上，为纳米物联网（IoNT）创建透明导电薄膜（tcf）。目前的AgNWs批量生产涉及选择性分离和浓缩所需AgNWs的昂贵步骤。此外，AgNWs在恶劣环境中容易氧化。本项目研究了一种用于制造单分散AgNWs的微流体系统，该系统具有可控的长度和宽高比，并具有足够的浓度用于高性能tcf。微流反应器连接到3D打印机，用于连续制造和打印基于agnw的tcf，在保持高打印质量的同时降低成本。利用x射线吸收光谱法对微流体合成过程进行现场监测，为了解反应机理提供了基础。化学反应的机理知识有助于实现对AgNWs长径比和产率的控制。用钯纳米粒子通过用钯阳离子取代银来修饰AgNWs，以达到抗氧化的稳定性。该研究推进了AgNW tcf的低成本，环境稳定，具有柔性/可拉伸特性，在IoNT设备等应用中需要，具有推进柔性电子领域的高潜力。该项目由先进制造计划和促进竞争研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This research aims to discover a new technique for the economical manufacture of silver nanowire transparent conductive films for the Internet of Nano Things. The Internet of Nano Things promises to connect a new generation of sensors, transducers, data processors and communication devices for a smart and connected world. A vital component of all nanodevices is transparent conductive films, generally made of silver nanowires. Current manufacture of silver nanowires is costly as it involves multi-step batch production. This award investigates a new approach for large-scale manufacture of silver nanowires with direct coupling with a three-dimensional printing system for patterning of transparent conducting films. The reduced cost of transparent conducting films and print-on-demand silver nanowires hasten the adoption of devices for the Internet of Nano Things, which contributes to the U.S. economy and prosperity. This research combines aspects of manufacturing, material science, nanotechnology, chemistry, and engineering. Students actively participate in research thus achieving engineering expertise in advanced manufacturing, which is important to U.S. industry. Undergraduate and graduate students, particularly from under-represented groups, are encouraged to participate in research and training.This project studies the reaction conditions and mechanisms in a continuous reactor to produce silver nanowire (AgNW)-based conductive inks that can be continuously printed onto flexible substrates to create transparent conducting films (TCFs) for the Internet of Nano Things (IoNT). The current batch production of AgNWs involves the costly steps of selective separation and concentration of the desired AgNWs. In addition, AgNWs are prone to oxidation in harsh environments. This project studies a millifluidic system for the manufacture of monodispersed AgNWs with controllable length and aspect ratio and sufficient concentration for high performance TCFs. The millifluidic reactor is connected to a 3D printer for continuous manufacture and printing of AgNW-based TCFs with a reduction in cost while maintaining high print quality. In-situ monitoring of the millifluidic synthesis by X-ray absorption spectroscopy provides fundamental understanding of the reaction mechanisms. Mechanistic knowledge of the chemical reactions helps to achieve control over the aspect ratio and yield of the AgNWs. The AgNWs are modified using Pd nanoparticles via the galvanic replacement of Ag with Pd cations to achieve stability against oxidation. This research advances AgNW TCFs that are low cost, environmentally stable, with flexible/stretchable characteristics needed in applications such as IoNT devices with high potential for advancing the field of flexible electronics.This project is jointly funded by the Advanced Manufacturing Program and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.