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. DerbyUniversity/Institution：University of Minnesota Twin Cities题目：Growth of Crystalline ZnO Nanowires from Solution：From Theory to Application 将进行多尺度建模和实验的组合程序，以了解纳米线形式的晶体氧化锌（ZnO）生长的最重要方面。这些结构的阵列是从过饱和液相生长的，并且对于基于硅藻土的染料敏化太阳能电池的制造特别感兴趣。这些低成本的光伏器件由于其极低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，但缺乏工艺水平变量对这些结构制造的影响的定量知识。提高这些设备的关键是一个更根本的理解的机制，其中的晶体纳米线从液体solution.The拟议工作的总体目标是发展和验证的基本，机械模型描述的晶体从液相生长和应用这些模型，以更好地了解ZnO纳米线晶体的生长。需要这样的知识来将生长条件与晶体结构完整性和组成的微观性质以及晶体形状的特征联系起来，即，生长习性和尺寸，影响纳米线阵列的密度。基于相场方法的多尺度理论模型将被开发来模拟过饱和液体中晶体表面上的纳米尺度生长螺旋。实验将在ZnO的溶液生长上进行，该实验利用新颖的纳米压痕技术来选择性地通过种子纳米晶体阵列放置位错。生长动力学将测量纳米线没有和生长螺旋，已经从这些位错演变。理论和实验将被应用到测试的假设，在这个系统中的长径比纳米线主要是从与一个面上的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使仅靠理论或实验不可能取得的进展成为可能。智力优点：这项工作解决了晶体生长的基本科学问题，并明确了改善实际应用的目标。通过相场方法，体传输与分步生长动力学的耦合，将导致新的严格性和相关性的溶液晶体生长的多尺度模型。这样的模型将使溶液晶体生长过程中的流体流动，传质和界面动力学的耦合因素的基本探索。这项工作的一个具体成果将是更好地了解结晶，ZnOnanowires的液相生长。更广泛的影响：这项工作所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，特别是推进基于锗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工业中最常用的单元操作，用于纯化和分离在室温和压力下为固体的化学产品。溶液生长也用于生产许多无机晶体，从大规模光学材料的生长到外延层的生长。更广泛的活动包括多尺度建模和纳米技术的研究生教育，以及涉及明尼苏达州科学博物馆的公众推广计划。