Semiconductor Belts, Sheets, and Wires Having Idealized Optical and Transport Properties

具有理想光学和传输性能的半导体带、片材和线材

• 批准号: 1306507
• 负责人: William Buhro
• 金额: $ 45万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1306507&HistoricalAwards=false
• 关键词: Semiconductor; Belts; Sheets; Wires; Having

William E. Buhro is supported by the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry to perform a thorough experimental study of the synthesis and optical properties of 1D and 2D colloidal semiconductor nanocrystals optimized for long-range charge and energy (exciton) transport. An exciting aspect of 1D and 2D nanocrystals having extended length dimensions, such as quantum wires, quantum belts, nanoribbons, and nanosheets, is their potential for transporting energy and charge over lengths approaching the millimeter scale. As transport is intimately involved in nanoelectronics, nanophotonics, and solar-energy conversion, large potential advantages exist for the use of 1D and 2D nanocrystals in such applications. The semiconductor 1D and 2D nanocrystal fields are now poised for rapid development. As a result of recent advances in surface passivation, some resulting from the prior NSF funding to the PI, quantum wires and nanowires are now available with excellent passivation and optical properties, and further rapid advances appear imminent. The 2D colloidal nanocrystal field is in its infancy, surface passivation and optical properties are initially good, and the field is developing at a very fast pace. A catalog is being constructed of 1D and 2D nanocrystals capable of efficient long-range transport as well as corresponding synthetic and structural strategies. This work strives to solve a long-standing problem with the currently available 1D colloidal nanowires, which are poorly passivated and have correspondingly poor transport properties. The specific goals of the proposed work are to (1) advance core-shell strategies for optimizing the optical properties and photoluminescence efficiencies of semiconductor quantum wires, by oxidative substitution, and by the new colloidal atomic-layer-deposition (c-ALD) method, (2) isolate and further characterize magic-size II-VI nanoclusters to provide experimental structural and spectroscopic data, (3) investigate magic-size nanoclusters as low-temperature nanocrystal precursors, (4) develop methods for gaining control over quantum-belt lengths, widths, and thicknesses, and (5) explore the synthesis and spectroscopic properties of quantum platelets and sheets of II-VI, IV-VI, and I-III-VI semiconductors.There is considerable interest in incorporating semiconductor nanocrystals into next-generation devices for solar-energy conversion. Solar cells constructed from semiconductor nanostructures are expected to be fabricated more economically than the traditional silicon-based devices, and to have other application advantages. A solar cell functions by capturing light energy and converting it to energetic positive and negative electric charges, which are then separated and transported to opposite electrodes in the cell. This provides electrical energy for charging a battery or operating an electrical appliance. The critical steps are thus the efficient separation of the positive and negative charges and the efficient transport of those charges to the electrodes. 1D and 2D semiconductor nanocrystals are targeted for use in new solar-cell designs because they can in principle transport energy and charge over long distances. However, efficient transport requires that charges not be trapped at defect sites in the nanocrystals. This project is aiming to identify and eliminate those trap-site defects, enabling the application of 1D and 2D semiconductor nanocrystals in solar cells, nanoelectronics, and in small-scale devices for light detection and generation. The broader impacts include technological advances to assist in addressing the nation's energy challenge. The PI also has an excellent record of training women and members of underrepresented groups, thereby increasing the diversity of the nation's technological work force. The PI is co-leading an effort at Washington University to increase the retention of undergraduate women in science, technology, engineering, and math (STEM) fields.

William E.Buhro在化学系大分子、超分子和纳米化学计划的支持下，对一维和二维胶体半导体纳米晶的合成和光学性质进行了深入的实验研究，这些纳米晶针对远程电荷和能量(激子)传输进行了优化。具有扩展长度维度的一维和二维纳米晶体，如量子线、量子带、纳米带和纳米薄片，令人兴奋的方面是它们在接近毫米尺度的长度上传输能量和电荷的潜力。由于传输与纳米电子学、纳米光子学和太阳能转换密切相关，因此在这些应用中使用一维和二维纳米晶体具有巨大的潜在优势。半导体一维和二维纳米晶领域现在正处于快速发展的阶段。由于最近在表面钝化方面的进展，其中一些是由于之前NSF对PI的资助，量子线和纳米线现在可以获得优异的钝化和光学性能，而且进一步的快速进展似乎迫在眉睫。二维胶体纳米晶领域正处于起步阶段，表面钝化和光学性能初步良好，该领域正在以非常快的速度发展。一维和二维纳米晶体的目录正在构建中，这些纳米晶体能够有效地进行长距离传输，以及相应的合成和结构策略。这项工作致力于解决目前可用的一维胶体纳米线的一个长期存在的问题，这些纳米线钝化得很差，并且相应地具有较差的传输性能。提出的工作的具体目标是：(1)通过氧化取代和新的胶体原子层沉积(c-ALD)方法，提出用于优化半导体量子线的光学性质和光致发光效率的核-壳策略，(2)分离并进一步表征魔术尺寸的II-VI纳米团簇，以提供实验结构和光谱数据，(3)研究魔术尺寸纳米团簇作为低温纳米晶体前体，(4)开发获得对量子带长度、宽度和厚度的控制的方法，以及(5)探索II-VI的量子小片和片的合成和光谱性质，IV-VI和I-III-VI半导体。将半导体纳米晶引入用于太阳能转换的下一代器件方面有相当大的兴趣。由半导体纳米结构构建的太阳能电池有望比传统的硅基器件更经济地制造，并具有其他应用优势。太阳能电池的工作原理是捕捉光能，并将其转化为含能的正电荷和负电荷，这些电荷随后被分离并传输到电池中的相反电极。它为电池充电或操作电器提供电能。因此，关键步骤是有效地分离正负电荷，并将这些电荷有效地输送到电极上。一维和二维半导体纳米晶体被用于新的太阳能电池设计，因为它们原则上可以远距离传输能量和电荷。然而，有效的传输要求电荷不被捕获在纳米晶体中的缺陷位置。该项目旨在识别和消除这些陷阱位缺陷，使一维和二维半导体纳米晶体在太阳能电池、纳米电子学以及用于光检测和产生的小型设备中得到应用。更广泛的影响包括帮助应对国家能源挑战的技术进步。在培训妇女和代表人数不足的群体成员方面，该协会也有很好的记录，从而增加了国家技术劳动力的多样性。PI正在华盛顿大学共同领导一项努力，以增加科学、技术、工程和数学(STEM)领域的本科生女性留存率。