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

纽约叶史瓦大学的Anatoly Frenkel得到了化学系大分子、超分子和纳米化学项目的国际化学合作（ICC）资助，研究掺杂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特性，尽管以有意和可控的方式做到这一点的能力是一个仍在发展的科学领域。在这个项目中，将铜、银和金等杂质以控制的量添加到包含期望的半导体晶体前体的系统中。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。这项研究对光学、电子、太阳能捕获和其他领域应用的潜在新构建模块的开发具有广泛的影响。这项工作正在对参与这项独特的国际合作的学生的教育机会产生进一步广泛的影响。这项工作包括与耶路撒冷（以色列）希伯来大学的Uri Banin进行国际合作。Banin教授的工作得到了美国-以色列两国科学基金会（BSF）的支持。胶体半导体纳米晶体（NCs）表现出独特的尺寸依赖效应，作为光学、光电子、太阳能和生物学等领域的潜在基础材料，正受到广泛的研究。通过胶体合成方法获得了对这种nc的大小、形状和组成的精确控制。然而，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)实现对掺杂半导体nc的合成控制的新水平，这将为研究掺杂机制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进行表征。该研究为掺杂纳米碳管的研究提供了几个重要的开放性方面：(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NC晶格的机制的理解；(3)研究掺杂纳米碳化物的结构、电子、光学和电荷输运性质；(4)研究胶体纳米碳的形成动力学、溶解度极限和稳定性。此外，这项工作为这些系统的理论认识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.