Growth of crystalline ZnO nanowires from solution: From theory to application

从溶液中生长结晶氧化锌纳米线：从理论到应用

• 批准号: 0729924
• 负责人: Jeffrey Derby
• 金额: $ 17.71万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0729924&HistoricalAwards=false
• 关键词: Growth; crystalline; ZnO; nanowires; solution

Proposal Number: CBET: 0729924 Principal Investigator: Jeffrey J. DerbyUniversity/Institution: University of Minnesota Twin CitiesTitle: Growth of Crystalline ZnO Nanowires from Solution: From Theory to Application A combined program of multi-scale modeling and experiments will be conducted to understand the most significant aspects of the growth of crystalline zinc oxide (ZnO) in the form of nanowires. Arrays of these structures are grown from supersaturated liquid phases and are of particular interest for the fabrication of nanowire-based, dye-sensitized solar cells. These low-cost, photovoltaic devices are especially attractive due to their potential for very low cost and good efficiency. The quality, microstructure, and dimensions of the ZnO nanowire array determine the solar cell's performance, yet quantitative knowledge of the effects of process-level variables on the fabrication of these structures is lacking. Key to improving these devices is a more fundamental understanding of the mechanisms by which the crystalline nanowires grow from liquid solution.The overall objectives of the proposed work are the development and validation of fundamental, mechanistic models describing the growth of crystals from the liquid phase and the application of these models to better understand the growth of ZnO nanowire crystals. Such knowledge is needed to link growth conditions to microscopic properties of crystalline structural perfection and composition, as well as characteristics of crystal shape, i.e., growth habit and size, that affect the density of the nanowire arrays. Multi-scale, theoretical models, based on the phase-field approach, will be developed to simulate nano-scale growth spirals on crystal surfaces in a supersaturated liquid.Experiments will be conducted on the solution growth of ZnO that utilize novel nano-indentation techniques to selectively place dislocations through an array of seed nanocrystals. Growth kinetics will be measured for nanowires both without and with growth spirals that have evolved from those dislocations. Theory and experiment will be applied to test the hypothesis that long-aspect-ratio nanowires in this system arise primarily from kinetic factors associated with a growth spiral on one face. The synergy between model and experiment will enable advances not possible by theory orexperimentation alone. Intellectual merit: The work addresses fundamental scientific issues of crystal growth together with a clear goal toward improving a practical application. The coupling of bulk transport with step growth kinetics, via the phase-field approach, will result in multi-scale models for solution crystal growth of new rigor and relevance. Such models will enable a fundamental exploration of the coupled factors of fluid flow, mass transfer, and interfacial kinetics in solution crystal growth processes. A specific outcome of this work will be a greater understanding of the liquid-phase growth of crystalline, ZnOnanowires. Broader impacts: Results obtained by this work will increase the fundamental understanding of how crystals grow from liquid solutions and specifically advance nanowire-based, dye sensitized solar cells. Other applications involving solution crystal growth are also likely to be affected by the understanding provided by this research. For example, solution crystallization is the most commonly used unit operation in the chemical and pharmaceutical industries for the purification and separation of chemical products that are solids at room temperature and pressure. Solution growth is also applied for the production of many inorganic crystals, ranging from the growth of large-scale optical materials to the growth of epitaxial layers. Broader activities include the education of graduate students in multi-scale modeling and nanotechnology, as well as an outreach program for the general public involving the Science Museum of Minnesota.

提案编号：CBET：0729924主要研究者：Jeffrey J. Derboruniversity/机构：明尼苏达大学双胞胎Citiestle：Crystalline Zno nanowires的增长从解决方案：从理论到应用程序的组合程序，将进行多规模建模和实验的组合程序，以了解最重要的ZN成长ZN的成长（ZN）ZN的成长（ZN）的形成（Zn纳米线。这些结构的阵列是从过饱和液相生长的，对于制造基于纳米的染料，染料敏感的太阳能电池特别感兴趣。这些低成本的光伏设备由于其具有非常低的成本和良好效率的潜力而特别有吸引力。 ZnO纳米线阵列的质量，微观结构和尺寸决定了太阳能电池的性能，但缺乏对过程级变量对这些结构制造的影响的定量知识。改善这些设备的关键是对液体溶液中结晶纳米线生长的机制的更基本的理解。拟议工作的总体目标是开发和验证基本的机械模型，描述了液相的晶体生长以及这些模型的应用以更好地了解Zno Nanowire晶体的生长。需要这样的知识将生长条件与晶体结构完美和组成的显微镜特性以及晶体形状的特征，即生长习惯和大小影响影响纳米线阵列的密度。将开发基于相田方法的多尺度理论模型，以模拟超饱和液体中晶体表面上的纳米尺度生长螺旋。将在使用ZnO的溶液生长上进行验证，该溶液使用新型的纳米识别技术的溶液生长，以通过一系列播种型nan nanocrystals选择性地放置位错。生长动力学将用于没有生长螺旋的纳米线，这些螺旋形成这些脱位的生长动力学。理论和实验将用于检验以下假设：该系统中的长期观测纳米线主要来自与一个面部生长螺旋相关的动力学因素。模型和实验之间的协同作用将仅通过理论观察才能实现进步。知识分子的优点：这项工作解决了水晶增长的基本科学问题，以及改善实际应用的明确目标。通过相田方法将散装传输与步进生长动力学的耦合将导致多尺度模型，用于新的严格和相关性的溶液晶体生长。这样的模型将对溶液晶体生长过程中流体流，传质和界面动力学的耦合因子进行基本探索。这项工作的具体结果将是对晶体，Znonanowires的液相生长的更多了解。更广泛的影响：这项工作获得的结果将增加对晶体如何从液体溶液中生长的基本理解，并特别推进基于纳米线的染料敏化太阳能电池。涉及溶液晶体生长的其他应用也可能会受到本研究提供的理解的影响。例如，溶液结晶是化学和制药行业中最常用的单位操作，用于在室温和压力下纯化和分离化学产品。溶液的生长还用于生产许多无机晶体，范围从大规模光学材料的生长到外延层的生长。更广泛的活动包括对多尺度建模和纳米技术的研究生的教育，以及针对明尼苏达州科学博物馆的公众提供的外展计划。