International Collaboration in Chemistry: Doping of Colloidal Semiconductor Nanocrystals: Synthesis, Diffusion Mechanisms, Structure and Optoelectronic Properties

纽约Yeshiva大学的Anatoly Frenkel得到了化学系大分子、超分子和纳米化学计划的支持，该计划获得了国际化学合作(ICC)赠款，以研究掺入特定杂质的小型半导体晶体。这些杂质使研究人员能够操纵半导体的电子性质，尽管以故意和受控的方式做到这一点的能力是一个仍在开发中的科学领域。在这个项目中，铜、银和金等杂质被以受控的数量添加到一个包含所希望的半导体晶体的前体的系统中。然后使用一种涉及X射线的技术来研究杂质的位置和性质。这项工作使研究人员能够详细了解杂质是如何进入半导体晶体的，以及它们是否以及如何在晶体结构中移动。这项研究对开发潜在的新构建块在光学、电子、太阳能捕获和其他领域的应用具有广泛的影响。这项工作对参与这一独特国际合作的学生的教育机会产生了进一步广泛的影响。这项工作包括与耶路撒冷希伯来大学(以色列)的乌里·巴宁的国际合作。巴宁教授的工作得到了美国-以色列双国科学基金会(BSF)的支持。胶体半导体纳米晶(NCS)表现出独特的尺寸依赖效应，正在被广泛研究，作为潜在的构建块在光学、光电子学、太阳能和生物学中的应用。通过胶体合成方法，已经获得了对这种NCS的大小、形状和组成的精细控制。然而，进行有意掺杂的能力以及了解掺杂剂对NC性能的影响仍然是一个难以捉摸的挑战。该项目有两个主要的计划重点：1)实现掺杂半导体纳米管的新的合成控制水平，这将为研究掺杂机理提供一系列定义良好的模型系统，以及2)使用先进的X射线吸收光谱、电子显微镜和拉曼光谱方法来表征它们。这项研究有助于研究掺杂纳米碳管的几个重要的开放方面：(1)掺杂半导体纳米碳管的合成和先进的结构表征；(2)建立对杂质原子进入纳米晶格的机制的理解；(3)研究掺杂纳米碳管的结构、电子、光学和电荷输运性质；(4)研究胶体纳米碳管的形成动力学、溶解度极限和稳定性。此外，这项工作还为从理论上理解这些体系提供了新的化学和物理数据。

Anatoly Frenkel of Yeshiva University in New York is supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry for an International Collaboration in Chemistry (ICC) grant to study small semiconductor crystals that have been doped with specific impurities. These impurities allow the investigators to manipulate the electronic properties of the semiconductors, although the ability to do this in an intentional and controlled way is an area of science that is still developing. In this project, impurities such as copper, silver and gold are added in controlled amounts to a system containing the precursors of the hoped-for semiconductor crystals. The location and nature of the impurities is then studied using a technique involving X-rays. The work is allowing the investigators to develop a detailed understanding of how the impurities find their way into the semiconductor crystal and whether and how they move around within the crystal structure. This research is having a broad impact on the development of potential new building blocks for applications in optics, electronics, solar energy capture, and other areas. The work is having a further broad impact on the educational opportunities of the students who are involved in this unique international collaboration. The work includes an international collaboration with Uri Banin of the Hebrew University, Jerusalem (Israel). Professor Banin's work is supported by the United States - Israel Binational Science Foundation (BSF).Colloidal semiconductor nanocrystals (NCs) manifest unique size-dependent effects and are being intensively investigated as potential building blocks for applications in optics, optoelectronics, solar energy and biology. Exquisite control over the size, shape, and composition of such NCs has been gained through colloidal synthesis approaches. However, the ability to perform intentional doping, and understanding the effects of dopants on the NC properties remains an elusive challenge. This project has two main programmatic foci: 1) achieving a new level of synthetic control for doped semiconductor NCs that will provide a series of well-defined model systems for studying doping mechanisms, and 2) the use of advanced X-ray absorption spectroscopy, electron microscopy and Raman spectroscopy methods for their characterization. The study is contributing to several important open aspects concerning doped NCs: (1) Synthesis of doped semiconductor NCs and advanced structural characterization; (2) establishing an understanding of the mechanisms governing the incorporation of impurity atoms into a NC lattice; (3) studying the structural, electronic, optical and charge transport properties of doped NCs; and (4) investigating the formation kinetics, solubility limit and stability of colloidal NCs. In addition, this work is providing new chemical and physical data for the theoretical understanding of these systems.