NIRT: Synthesis, Electrical and Optical Properties of Metal-Molecule-Metal Junctions formed by Self-Assembly

本项目旨在合成金属-有机半导体分子-金属结构，通过DNA预先组装或模板化，或作为化学吸附的金纳米颗粒/纳米线直接连接到分子上的纳米级金属接触。金属触点将形成分子器件的欧姆触点，用于从直流到微波频率的电路。由于整体杂化结构将比感兴趣的有机分子长得多，因此不需要精确制造的超小间隙。在光学频率下，金属接触将在分子装置周围形成一个电磁腔，增强光场，用于单分子光谱测量。这些新的纳米级物体的自组装将从理论和实验两方面进行研究。将制造电子设备来研究单分子中的电荷传输。这些独特的纳米结构可能会产生新的电学、光学和物理现象。在这项工作中形成的开放平面几何结构有望允许使用附近的强耦合栅电极对电子态进行静电修饰，并将减少附近金属电极的荧光猝灭。单分子晶体管和发光二极管可以从所提出的结构中产生。所开发的方法将为开发分子电子和光学器件并将其集成到复杂电路中奠定基础。智力上的功绩。跨学科的根本性进展对于纳米设备的进步和理解它们的行为是必不可少的。分子合成、自组装和电荷传输是利用有机分子实现纳米器件的重要组成部分。在这类问题上协调一致的团队攻击可以促进单分子设备的状态。该项目将由两名化学家、一名固体物理学家、一名光谱学家和一名理论家组成的团队进行，以及来自行业、国家实验室和外国大学的合作者，他们拥有聚合物合成、表面化学、生物化学、DNA自组装、DNA金属化、光谱学、电荷传输、流体动力学模拟和器件制造方面的专业知识。更广泛的影响。该项目可能导致一种与单分子进行电接触的新方法，这将使研究具有不同化学功能和长度的单分子的电荷传输以及测量限制在纳米间隙中的单分子产生的独特光学性质成为可能。这项工作不仅将回答长度为5-100 nm的分子中分子内电荷传输机制的基本问题，还将为有机分子是否具有足够的纳米电子学性能以及有机半导体分子在电极之间的排列是否会显著提高分子器件的迁移率等技术问题提供答案。该项目还利用DNA-聚合物-DNA和纳米颗粒-分子-纳米颗粒结构的自组装方法，使用电泳和介电泳法，使单个有机半导体分子能够进行电连接。PIS将与现有的NSF中心和斯坦福大学科学外展办公室密切合作，覆盖从K-12到社区大学、本科生和研究生的广泛人群，并为未来的教师培养新的科学和技术领域。该项目每年为少数族裔和/或女性社区大学生提供两个实习职位。暑期期间还将为一名初中或高中教师提供一个研究职位；在暑期研究结束后，PI将继续与他们合作制定他们的教育计划。PIS还将通过公共网站和参与各种社区活动来接触普通公众。参与该项目的研究生和博士后将积极互动，并有机会与来自行业、国家实验室和国际合作者的研究人员互动。他们将具备技术工程技能、基本的科学理解和沟通技能，并准备为纳米科学和纳米技术做出贡献。

This project aims to synthesize metal-organic semiconducting molecule-metal structures with nanoscale metallic contacts pre-assembled or templated by DNAs, or directly connected to the molecule as chemisorbed gold nanoparticles/nanowires. The metallic contacts will form ohmic contacts to molecular devices for circuits from DC to microwave frequencies. Precisely fabricated, ultrasmall gaps are not needed since the overall hybrid structure will be much longer than the organic molecule of interest. At optical frequencies, the metallic contacts will form an electromagnetic cavity around the molecular device, enhancing optical fields to be utilized in single-molecule spectroscopic measurements. Self-assembly of these new nanoscale objects will be investigated both theoretically and experimentally. Electrical devices will be fabricated to study charge transport through single molecules. New electrical, optical and physical phenomenon may arise from these unique nanoscale structures. The open planar geometry formed in this work is expected to allow electrostatic modification of electronic states using a nearby strongly-coupled gate electrode, and will reduce fluorescence quenching by nearby metallic electrodes. Single-molecule based transistors and light-emitting diodes may be generated from the proposed structures. The methods developed will lay the groundwork for developing molecular electronic and optical devices and integrating them into complex circuits. Intellectual Merit. Fundamental advances across disciplines are essential to the advancement of nanoscale devices and to understanding their behavior. Molecular synthesis, self-assembly, and charge transport are essential components for realizing nanoscale devices with organic molecules. A coordinated team attack on such issues can advance the state of single-molecule devices. This project will be carried out by a team of two chemists, one solid-state physicist, one spectroscopist, and one theorist together with collaborators from industry, national labs, and foreign universities with expertise in polymer synthesis, surface chemistry, biochemistry, DNA self-assembly, DNA metallization, spectroscopy, charge transport, fluid dynamics simulation, and device fabrication. Broader Impacts. This project may result in a new approach to make electrical contacts to single molecules, which will allow study of charge transport through single molecules with different chemical functionalities and length as well as measurement of unique optical properties arising from a single molecule confined in a nanogap. The proposed work will not only answer fundamental questions of intramolecular charge transport mechanisms in molecules with length scale of 5-100 nm, it will also provide answers to technological questions of whether organic molecules have sufficient performance for nanoelectronics and whether the mobility of molecular devices will be dramatically increased by alignment of organic semiconducting molecules between electrodes. This project also utilizes methods to self- assemble DNA-polymer-DNA and nanoparticle-molecule-nanoparticle structures using electrophoresis and dielectrophoresis to allow electrical connections to be made to single organic semiconducting molecules. The PIs will work closely with existing NSF centers and the Stanford Office of Science Outreach to reach a broad population ranging from K-12, community college, undergraduate, and graduate students as well as to prepare teachers of tomorrow for new areas of science and technology. Two internship positions every year for minority and/or women community college students are integral to the project. One research position per year will also be provided to a middle school or high school teacher during the summer; PIs will continue to work with them to develop their education plans after their summer research. PIs will also reach out to the general public through a public website and participation in various community events. The graduate students and postdoc involved in the project will actively interact with each other and have the opportunity to interact with researchers from industry, national labs, and international collaborators. They will be well equipped with a combination of technical engineering skills, basic scientific understanding, and communication skills, and poised to contribute to nanoscience and nanotechnology.