Continuous Manufacturing of Lead-free Halide Perovskite Nanocrystals Using a Microreactor System

这项拨款支持研究，以提高制造系统的知识，如高效太阳能电池，价格合理的光伏电池，柔性彩色显示器和生物传感器，更快，更便宜，并且不需要传统制造方法带来的铅。无铅金属卤化物钙钛矿纳米晶体可以发出从紫外线到可见光的光。它们的广泛使用取决于其可扩展、低成本制造技术的发展。它们也是有毒的铅基钙钛矿的替代品。大多数制备钙钛矿纳米晶体的方法都是基于单批方法，这限制了生产能力和产品的可变性。这里的研究将支持连续生产过程。在微流控微反应器系统中制造半导体纳米晶体的能力使其具有所需的尺寸、形状和性能，从而加速了其在各种工业中的应用。制备高质量无铅卤化物钙钛矿纳米晶体的可扩展方法的成功开发，为连续制造无铅金属卤化物钙钛矿纳米晶体的发展提供了条件，从而推动了无机半导体基础科学的进步。这项研究的结果有助于保持和提高美国在这些技术方面的竞争力和领导地位，从而为国家的繁荣做出贡献。该研究的多学科性质为美国工业提供了具有先进材料和制造知识和技能的未来劳动力。特别努力的重点是妇女和代表性不足的少数民族的参与和培训。采用微流控-微反应器系统可以克服单批制备钙钛矿纳米晶在温度、时间和局部浓度等工艺参数控制上的困难，为短时间、高通量制备钙钛矿纳米晶提供了可能。由于缺乏对流体系统中控制纳米晶体形成和生长的热力学和动力学的理解，阻碍了微流体-微反应器系统生产具有相同几何形状的单分散纳米晶体的发展。本研究旨在开发一种基于聚四氟乙烯的微反应器，用于连续制备金属卤化物钙钛矿纳米晶体，并对其形成和生长的基本机制进行研究。研究小组建立了加工参数（如浓度、温度、停留时间和流速）与钙钛矿纳米晶体特征（如形貌和尺寸）之间的相关性。该团队开发了可以定量分析微反应器系统中半导体纳米晶体生长的数值模型。这些相关性提供了对控制纳米晶体尺寸分布和形态的动力学的基本理解，并有助于优化微反应器设计，以实现高质量钙钛矿纳米晶体的可扩展制造。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 grant supports research that advances knowledge to manufacture systems such as high efficiency solar cells, affordable photovoltaics, flexible color displays and biosensors more quickly, less expensively and free of the lead that results from more traditional manufacturing approaches. Lead-free metal halide perovskite nanocrystals emit light from the ultraviolet to the visible. Their wide use is dependent on the development of techniques for their scalable, low cost manufacturing. They are also candidates for replacement of lead-based perovskites, which are toxic. Most methods to manufacture perovskite nanocrystals are based on single batch approach, which has limited production capacity and considerable product variability. Research here will support a continuous manufacturing process. The ability to manufacture semiconductor nanocrystals in microfluidic-microreactor systems enables their fabrication with the desired size, shape and properties, thus, accelerating their applications in a variety of industries. The successful development of a scalable method to manufacture high-quality lead-free halide perovskite nanocrystals enables the development of continuously manufactured lead-free metal halide perovskite nanocrystals that leads to progress in the fundamental science of inorganic semiconductors. The results from this research help maintain and enhance U.S. competitiveness and leadership in these technologies, thus contributing to the nation's prosperity. The multidisciplinary nature of this research prepares the needed future workforce for U.S. industries with knowledge and skills in advanced materials and manufacturing. Special efforts are focused on the participation and training of women and under-represented minorities.Using microfluidic-microreactor systems can overcome the difficulty in controlling the processing parameters, such as, temperature, time and local concentration for the fabrication of perovskite nanocrystals in the single batch methods and offer a possible approach to manufacture them with very short reaction time and high throughput. The lack of an understanding of the thermodynamics and kinetics controlling the formation and growth of nanocrystals in a fluidic system has hindered the development of microfluidic-microreactor systems to produce monodispersed nanocrystals of the same geometrical shapes. This research is to develop a polytetrafluoroethylene-based microreactor in a microfluidic system with in-line monitoring for continuous fabrication of metal halide perovskite nanocrystals and to investigate the fundamental mechanisms controlling their formation and growth. The research team establishes correlations between the processing parameters, such as, concentration, temperature, residence time and flow rate, and perovskite nanocrystal characteristics, such as, morphology and size. The team develops numerical models that can quantitatively analyze the growth of semiconductor nanocrystals in the microreactor system. These correlations provide fundamental understanding of the kinetics controlling the size distribution and morphologies of nanocrystals and help optimize the microreactor design for the scalable manufacturing of high-quality perovskite nanocrystals.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.