Reaction Limited Synthesis of Atomically-Defined Semiconductor Nanocrystals

原子定义的半导体纳米晶体的反应有限合成

• 批准号: 1710063
• 负责人: Mikhail Zamkov
• 金额: $ 35.08万
• 依托单位: Bowling Green State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1710063&HistoricalAwards=false
• 关键词: Reaction; Limited; Synthesis; Atomically; Defined; Reaction; Limited; Synthesis; Atomically; Defined

Non-technical Abstract:Colloidal nanostructures are emerging as attractive candidates for low-cost processing of next-generation optical and electronic materials. Their characteristic size falls within the unique length scale where inorganic semiconductors exhibit tunable, molecular-like properties while retaining a good thermal and photo-stability. The chemical synthesis of semiconductor nanostructures typically results in a large variety of particle shapes and sizes, which negatively affects the ensuing device performance. To address this issue, the project aims to explore an alternative synthetic strategy for growing uniform, atomically-defined semiconductor nanoparticles. The innovation lies in employing chemical rather than thermal growth, which benefits from reaction-controllable, incremental steps in the particle formation. This strategy enables an unprecedented precision in controlling both the shape and the uniformity of semiconductor nanostructures. The development of a synthetic methodology for growing atomically-defined colloidal nanoparticles can potentially affect a wide range of emerging technologies relying on solution processing of semiconductors. It is expected to result in improved electrical and optical performance of materials for the solar fuel generation and solid state lighting. The educational aspects of this project are planned to focus on elucidating students through research activities and curriculum development.Technical Abstract:The project aims to explore a reaction-limited growth of colloidal semiconductor nanocrystals in an effort to achieve a controllable evolution of particle shapes and sizes. Nanocrystal synthesis is typically performed via thermal activation of precursors which benefits from a fast, low-defect crystallization. As a diffusion-limited growth mechanism, however, the hot-injection strategy makes it inherently difficult to control the nanoparticle size dispersion, ligand coverage, and the cation-to-anion ratio across the sample. As a result, distinct optoelectronic properties of individual nanoparticles become inhomogenously broadened in assemblies. The present strategy employs the sequential deposition of fully saturated cationic and anionic monolayers onto small-diameter clusters, which leads to focusing of particle sizes with the increasing diameter. Each ionic layer is grown via a colloidal analog of the atomic layer deposition to keep precursors and nanocrystals in separate phases. As a result, a self-limited monolayer deposition becomes very effective leading to stoichiometrically defined surfaces at each ion growth cycle. It is expected that an improvement in nanoparticle uniformity down to atomically precise structures is attainable through this strategy. An improved control over the nanoparticle size dispersion is likely to advance the development of light-emitting devices, whereas a well-defined surface composition could avail film-based nanocrystal applications (solar cells, transistors).

非技术摘要：胶体纳米结构正在成为低成本处理下一代光学和电子材料的有吸引力的候选者。它们的特征大小属于独特的长度尺度，无机半导体表现出可调的，类似于分子的特性，同时保持良好的热和光稳定性。半导体纳米结构的化学合成通常会导致各种颗粒形状和尺寸，从而对随后的设备性能产生负面影响。为了解决这个问题，该项目旨在探索一种替代综合策略，以探索均匀，原子定义的半导体纳米颗粒。创新在于采用化学而不是热生长，这受益于反应控制的颗粒形成中的增量步骤。该策略在控制半导体纳米结构的形状和均匀性方面具有前所未有的精度。开发用于生长原子定义的胶体纳米颗粒的合成方法可能会影响依赖于半导体溶液处理的广泛的新兴技术。预计它将改善材料的电气和光学性能，以产生太阳能燃料的产生和固态照明。该项目的教育方面计划通过研究活动和课程开发阐明学生。技术摘要：该项目旨在探索胶体半导体纳米晶体的反应有限的增长，以实现可控制的颗粒形状和尺寸的可控制演变。纳米晶体的合成通常是通过热激活前体进行的，这些前体受益于快速，低缺陷的结晶。然而，作为一种扩散限制的生长机制，热注射策略使得在样品中控制纳米颗粒尺寸的分散体，配体覆盖范围以及阳离子与阳离子的比率本质上难以控制样品。结果，各个纳米颗粒的独特光电特性在组件中变得不宽大。目前的策略采用了完全饱和的阳离子和阴离子单层的顺序沉积到小直径簇上，这导致颗粒大小随直径的增加而聚焦。每个离子层都是通过原子层沉积的胶体类似物生长的，以将前体和纳米晶体保持在单独的相位。结果，自限制的单层沉积变得非常有效，导致每个离子生长周期在化学计量法上定义表面。可以通过这种策略可以实现纳米颗粒均匀性统一到原子精确结构的改善。对纳米颗粒尺寸色散的改进控制可能会推动发光设备的开发，而定义明确的表面组成可以利用基于膜的纳米晶体应用（太阳能电池，晶体管）。