EAGER: Emergent Quantum Confinement-Induced Properties of a New Class of Aromatic Ligand-Passivated Hybrid ITO Nanocrystals

纳米晶体（NC）具有十亿分之一米量级的无机核尺寸。将它们组装成更大的上层建筑是具有挑战性的。沿着这些路线，这个奖项，这是由材料研究部的固态和材料化学计划的支持，解决了现代纳米科学和纳米技术相关的研究的前沿。使用聚合物作为溶剂来合成超小的掺锡氧化铟（ITO）NCs，该项目的目标是在制造改进的光电器件（如光致发光器件、发光二极管、光电探测器和光催化太阳能燃料生产）中具有潜在应用的材料。该项目研究了适当选择的有机分子的表面附着如何产生混合ITO NC（人工分子），并因此改变了单个ITO NC及其组件的光电和电化学特性。传统上，通过改变NC的无机核尺寸来改变这些性质。由于不同的基本机制来调整性能，这项研究的影响预计将在新材料设计，推进纳米科学和材料化学的分子水平理解以及经济扩张和可持续性方面产生深远的影响。此外，该项目为研究生和本科生提供多学科研究培训机会，包括无机化学，材料科学和纳米技术。通过这些活动，主要研究者培养下一代STEM教育工作者和创新者。 配体钝化的纳米晶体（NC）引起化学家、物理学家和材料科学家的极大兴趣，因为NC-配体界面电子相互作用和键合极大地影响它们的化学和物理性质。通过这个固态和材料化学资助的项目，主要研究人员合成和表征了一类新的超小型量子限制混合ITO NCs。用独特设计的芳香配体官能化NC核心，使研究人员能够操纵无机（ITO核心）和有机表面配体之间界面能态的相互作用和电子耦合。这导致了新的结构-功能关系，这与以前传统的较大ITO NCs中的结构-功能关系有根本的不同。该项目的具体目标包括：（1）实验性地表征这类新的混合-ITO NC的光电性质，以理解存在于NC-配体界面处的基本化学和结构过程，并控制NC和配体的各个能量状态之间的电子耦合，（2）将实验光谱数据与计算模型相关联以预测NC尺寸和表面配体的电子和/或化学结构对光电性质的影响，和（3）可预测地将杂化ITO-NC组装成人造固体，然后测量固态中的电荷转移和传输性质，目的是理解控制这种现象的机制。总之，该项目的结果对于最终指导新型无机-有机杂化纳米材料的制备以提高固态光电器件和光催化剂的效率至关重要。

NON-TECHNICAL SUMMARY Nanocrystals (NCs) have inorganic core dimensions on the order of a billionth of a meter. It is challenging to assemble them into larger superstructures. Along these lines, this award, which is supported by the Solid State and Materials Chemistry program in the Division of Materials Research, addresses the forefront of modern nanoscience and nanotechnology-related research. Using polymers as solvents to synthesize ultrasmall tin-doped indium oxide (ITO) NCs this project targets a material with potential applications in fabrication of improved optoelectronic devices such as photovoltaics, light-emitting diodes, photodetectors, and photocatalytic solar fuel production. The project investigates how surface attachment of appropriately chosen organic molecules produces hybrid-ITO NCs (artificial molecules), and as a consequence alters the optoelectronic and electrochemical properties of the individual ITO NCs and their assemblies. Traditionally these properties are varied by changing the inorganic core size of NCs. Because of the different underlying mechanism to tune properties, the impact of this research is expected to be far-reaching in the context of new materials design, advancing molecular level understanding in nanoscience and materials chemistry, and economic expansion and sustainability. Additionally, this project provides multidisciplinary research training opportunities, including inorganic chemistry, materials science and nanotechnology, for graduate and undergraduate students. Through these activities the principle investigator fosters the next generation STEM educators and innovators. TECHNICAL SUMMARY Ligand-passivated nanocrystals (NCs) are of immense interest to chemists, physicists, and materials scientists, because NC-ligand interfacial electronic interactions and bonding greatly impact their chemical and physical properties. Through this Solid State and Materials Chemistry-funded project the principle investigator synthesizes and characterizes a new class of ultrasmall, quantum confined hybrid-ITO NCs. Functionalizing the NC core with uniquely designed aromatic ligands allows the researchers to manipulate the interaction and electronic coupling of interfacial energetic states between the inorganic (ITO core) and organic surface ligands. This leads to new structure-function relationships, which are fundamentally different from those previously characterized in traditional larger ITO NCs. Specific objectives of this project include: (1) experimentally characterizing the optoelectronic properties of this new class of hybrid-ITO NCs, both to understand the fundamental chemical and structural processes that exist at the NC-ligand interface and to control electronic coupling between individual energetic state of the NC and ligands, (2) correlating experimental spectroscopic data with computational models to predict the effects of the NC size and the electronic and/or chemical structure of surface ligands on optoelectronic properties, and (3) predictably assembling hybrid ITO-NCs into artificial solids and then measuring charge transfer and transport properties in the solid-state with the aim of understanding mechanisms controlling such phenomena. Taken together, results from this project are crucial in ultimately guiding the preparation of novel inorganic-organic hybrid nanomaterials to increase efficiency of solid-state optoelectronic devices and photocatalysts.