Molecules in 2D h-BN

在材料研究部固态和材料化学计划的支持下，威斯康星大学的迈克尔·阿诺德教授和他的研究小组将研究只有一个原子厚度的超薄片状材料的创造。这些材料将由含有元素硼和氮的电绝缘体制成。在薄片中嵌入和结合的将是超小的碳原子岛。这些岛屿将像分子一样小，并且，像正常分子一样，这些岛屿将具有精确定义的原子数量和精确定义的形状。碳岛也将模仿正常分子的电学和光学性质，但可以无缝集成并平坦地躺在硼-氮层中。像这样的材料，以这样的精度，以前从未被创造过。这个项目将解决合成这些材料的挑战，并发展创造它们所需的基本理解。这种原子定义良好的结构有可能被用作下一代过滤类材料，具有创纪录的效率，因为这种材料ˈ极薄，因此有望影响与空气和水的净化有关的具有社会重要性的应用。此外，由此产生的材料还有望拥有下一代电子和量子电子技术所需的特性，这对国防和繁荣至关重要。研究人员将通过计划的外展活动，例如通过威斯康星大学的獾谈话倡议，向公众传达所支持的研究和科学以及整个研究和科学的影响。技术综述分子是最终的纳米结构。它们的大小、形状和组成几乎可以无限调整，并且可以在大规模平行的规模上创建精确的复制品。分子ˈ的物理、电学和光学属性可以进行大量定制，以实现绝缘、半导体和金属行为，并操纵从紫外线到红外的光子。在这个项目中，在材料研究部固态和材料化学计划的支持下，我们将创建和探索类似分子-特别是多环芳烃(PAH)分子的类似物-这些分子不是自由的，而是共价嵌入在绝缘六方氮化硼(h-BN)的结晶单分子层中。虽然以前已经在h-BN中自上而下地构建了碳的纳米结构域，但这些结构域在形状和大小上都相对较大和/或无序，并且没有一个是以分子精度定义的。在这里，原子精确的碳域将实现，自下而上，通过使用多环芳烃分子本身来创建它们。嵌入的多环芳烃将提供传统分子的精确度和可调性，但以平面、固定化和原子薄的形式存在。分子嵌入型h-BN片材承诺出现以前不可能实现的现象--包括具有可广泛调节大小和形状的精确气孔的超薄材料(通过选择性碳蚀刻)，用于分子测序或筛分应用的h-BN片材(常规绝缘)，以及可单独寻址的固定单分子。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARY With this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, Professor Michael Arnold and his research group at the University of Wisconsin will investigate the creation of ultrathin, sheet-like materials that are only one atom thick. The materials will be created from an electrical insulator, containing the elements boron and nitrogen. Embedded and bonded within the sheets will be ultrasmall islands of carbon atoms. These islands will be as small as molecules, and, like normal molecules, these islands will have an exactly defined number of atoms and precisely defined shapes. The carbon islands will also mimic the electrical and optical properties of normal molecules but be seamlessly integrated and lie flat within the boron-nitrogen sheets. Materials like these, with this precision, have never been created previously. This project will address the challenge of synthesizing these materials and develop the fundamental understanding needed to create them. Atomically well-defined structures like these have the potential to be employed as next-generation filter-like materials with record-efficiency because of the materialsˈ extreme thinness and thus promise to impact applications of societal importance pertaining to the purification of air and water. The resulting materials moreover promise to possess properties needed for next-generation electronics and quantum electronics technologies, important for national defense and prosperity. The impact of the supported research and science, and of research and science in general, will be communicated to the public by the researchers through planned outreach activities, for example via the University of Wisconsin’s Badger Talks initiative. TECHNICAL SUMMARY Molecules are the ultimate nanostructures. Their size, shape, and composition can be nearly infinitely tuned, and exact replicas can be created on a massively parallel scale. Moleculesˈ physical, electrical, and optical properties can be vastly tailored – to realize insulating, semiconducting, and metallic behaviors and manipulate photons from the ultraviolet to the infrared. In this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research, we will create and explore analogs to molecules – specifically analogs to polycyclic aromatic hydrocarbon (PAH) molecules – that are not free but covalently embedded, in-plane, in crystalline monolayer sheets of insulating hexagonal boron nitride (h-BN). While nanoscale domains of carbon have been fabricated from the top-down in h-BN previously, these domains have been relatively large and/or disordered in shape and size, and none have been defined with molecular precision. Here, atomically precise carbon domains will be realized, from the bottom-up, by using PAH molecules themselves to create them. The embedded PAHs will offer the exactness and tunablility of conventional molecules but in a planar, immobilized, and atomically thin form. Molecularly embedded h-BN sheets promise phenomena not previously possible – including exceptionally thin materials with exact pores of widely tunable size and shape (through selective carbon etching) for molecular sequencing or sieving applications, h-BN sheets (conventionally insulating) with functional semiconducting dopants, and immobilized single molecules that are individually addressable.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.