Understanding and Enhancing Electronic Coupling Between Metal Halide Perovskite Quantum Dots Through Surface Molecular Engineering

纳米粒子是极小的晶体。它们的尺寸可能只有几纳米，或者比一张纸薄10万左右，它们可以由许多不同类型的材料制成，包括半导体。当电子被压缩到非常小的半导体纳米晶体中时，它们就会受到量子限制，并出现新的特性，这些特性可以用于新技术中。在应用之前，研究人员必须学习如何将量子点（QDs）打包成固体，以便一个纳米粒子可以与另一个纳米粒子共享电子。在化学系大分子、超分子和纳米化学项目的支持下，来自加州大学圣克鲁兹分校（UCSC）的张金忠教授和袁平教授正在研究由一种叫做钙钛矿的新型半导体形成的量子点固体。与硅等传统半导体不同，钙钛矿是无机成分和有机分子的混合物，这就产生了不同寻常的特性。与他们的学生一起，张教授和平教授正在研究创造稳定的量子点固体的方法，在这种固体中电子很容易共享。他们的发现可能会影响从量子计算到太阳能电池的各种应用。该项目还为未来的科学家提供了先进实验和计算技术的培训机会。通过每年夏天举办的“太阳、光谱学和圣克鲁斯”活动，研究小组向当地的高中学生和教师介绍这个项目，以提高公众对科学的认识。该研究小组正在开发基于金属卤化物（MH）钙钛矿的新型半导体量子点固体。本研究解决了由于量子点之间的弱耦合而限制量子点固体电荷传输特性的挑战，从而阻碍了新兴技术中的器件应用。该项目系统地研究了决定钙钛矿量子点（PQDs）之间电子耦合的基本因素，如尺寸、形状和表面，通过开发设计配体来增强PQDs之间的耦合和稳定性。结合时间分辨光致发光、透射电子显微镜、红外光谱和超快泵浦探针等方法，表征了pdq之间的耦合和配体之间的相互作用。独特的导电或芳香配体分子有望稳定量子点并增强它们的电子耦合，从而使量子点固体在保持量子点新特性的同时表现出强电荷输运。基于最先进的量子力学方法的计算研究正在探索配体- pqd相互作用和pqd之间的耦合，以指导和证实实验研究。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Nanoparticles are extremely small crystals. They can be just a few nanometers in size, or about 100,000 thinner than a sheet of paper, and they can be formed from many different types of materials, including semiconductors. When the electrons are squeezed into very small semiconductor nanocrystals, they become quantum-confined and new properties emerge, which can be harnessed for use in new technologies. Before proceeding to applications, researchers must learn how to pack the quantum dots (QDs) together into solids so that one nanoparticle can share its electrons with another. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professors Jin Z. Zhang and Yuan Ping from University of California Santa Cruz (UCSC) are studying QD solids formed from a new class of semiconductors called perovskites. Unlike traditional semiconductors, such as silicon, perovskites are a mixture of inorganic components and organic molecules and this gives rise to unusual properties. Working with their students, Professors Zhang and Pin are developing ways to create stable QD solids where the electrons are easily shared. Their discoveries could impact applications ranging from quantum computing to solar cells. The project also provides training opportunities for future scientists in advanced experimental and computational techniques. Through their "The Sun, Spectroscopy, and Santa Cruz" events held each summer, the research groups are introducing the project to local high school students and teachers to enhance public awareness about science. The research team is developing novel semiconductor QD solids based on metal halide (MH) perovskites. This research addressws the challenge that charge transport properties of QD solids are often limited due to weak coupling between QDs, hindering device applications in emerging technologies. The project is systematically studying the fundamental factors, such as size, shape and surface, that determine the electronic coupling between perovskite QDs (PQDs) by developing designer ligands that enhance both the coupling between the PQDs and their stability. The coupling between PDQs and interaction between ligands are characterized using a combination of time-resolved photoluminescence, transmission electron microscopy, infrared spectroscopy, and ultrafast pump-probe methods. Unique conductive or aromatic ligand molecules are expected to both stabilize the QDs and enhance their electronic coupling so that the QD solids will exhibit strong charge transport while maintaining the novel properties of the QDs. Computational studies based on state-of-the-art quantum mechanical methods are exploring the ligand-PQD interaction and inter-PQD coupling to guide and corroborate experimental studies.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.