Microscopy of Functional Molecules

有机电子材料是富碳化合物，其组成和结构被定制以优化特定的功能性质，例如电荷迁移率、光电导性或发光/磷光。由于有机材料的制造和加工成本较低，并且它们可以沉积在低成本（柔性）基板上，因此有机薄膜现在是许多商业产品的重要部分，最值得注意的是已经出现在移动的手机和平板电脑上的高效、明亮和多彩的显示器。也有大量的研究工作来开发稳定的薄膜晶体管和光伏器件，以利用该技术低成本发电。 尽管有机薄膜电子学最近在商业上取得了成功，但在实现基于分子的电子学的全部潜力之前，仍然需要解决巨大的挑战。为了实现在电子器件中或作为器件使用廉价的原子级精确分子的这一愿景，需要测量和控制嵌入固态器件或传感器中的分子的功能性质的新方法。这是因为单分子器件的性质关键取决于分子构型的每个细节，包括与固态主体的接触。 在过去的五年中，扫描探针的能力有了显著的提高，这对表面分子的研究有重要的意义。这些能力包括：以亚分子分辨率测量分子的电致发光，清楚地分辨碳原子之间的单个共价键，区分共价键的键级，并探测单个分子内的电荷分布。其中一些进展取决于用“探针”粒子（CO或CO2）创建原子级精确尖端的能力。其他则取决于石英杠杆（qPlus传感器）提供的稳定性。 在本提案中，我们试图通过利用这些新功能来解决基于分子的电子学的巨大挑战。我们的长期目标是在原子水平上控制有机-无机界面。作为实现这一目标的一步，我们将测量和操纵分子在表面的功能特性，并研究一种新的方法，将分子连接到金属表面使用n-杂环卡宾。 该研究计划是国际性的，多学科的和合作的。它涉及化学家，谁将合成分子，三个理论小组，谁将执行第一原理计算，和三个实验小组，谁拥有互补的专业知识，以我的小组在女王。加拿大研究生将与理论家密切合作，并前往我们的实验合作者，以利用在低温（1 K），高磁场（8 T）和光检测下工作的扫描探针显微镜。

Organic electronic materials are carbon-rich compounds with a composition and structure that is tailored to optimize a particular functional property such as charge mobility, photoconductivity or luminescence/phosphorescence. Because the manufacturing and processing costs of organic materials are low, and they can be deposited on low cost (flexible) substrates, organic thin films are now important parts of many commercial products, the most notable being the high efficiency, bright and colorful displays that have appeared on mobile phones and tablets. There is also significant research effort to develop stable thin-film transistors and photovoltaic devices for low cost energy generation with this technology.   Despite the recent commercial success of organic thin-film electronics, grand challenges remain to be solved before the full potential of molecule-based electronics can be realized. To fulfill this vision of using inexpensive, atomically precise molecules in electronic devices or as devices, new ways of measuring and controlling the functional properties of molecules embedded in a solid state device or sensor are required. This is because the properties of single molecule devices depend, crucially, on every detail of the molecule’s configuration, including the contact to the solid state host.      In the last five years, there have been dramatic improvements in the capabilities of scanning probes that have important implications for the study of molecules at surfaces. These include the ability to: measure electroluminescence from molecules with sub-molecular resolution, clearly resolve single covalent bonds between carbon atoms, discriminate the bond order of covalent bonds, and probe the charge distribution within single molecules. Some of these advances depend upon the ability to create atomically precise tips with 'probe' particles (CO or Xe). Others depend on the stability afforded by quartz cantilevers (qPlus sensors). In this proposal, we seek to address the grand challenges of molecule-based electronics by exploiting these new capabilities. Our long term goal is atomic-level control of the organic-inorganic interface. As a step towards this, we will measure and manipulate the functional properties of molecules at surfaces and investigate a new way of attaching molecules to metal surfaces using n-heterocyclic carbenes.  The research program is international, multidisciplinary and collaborative. It involves Chemists, who will synthesize molecules, three theoretical groups, who will perform first principles calculations, and three experimental groups, who possess complementary expertise to my group at Queen's. Canadian graduate students will work closely with theorists and travel to our experimental collaborators to take advantage of scanning probe microscopes that operate at low temperature (1 K), at high magnetic field (8 T) and with light detection.