Collaborative Research: Directing Charge Transport in Hierarchical Molecular Assemblies

在这个由化学系高分子、超分子和纳米化学计划资助的项目中，德克萨斯A&A&M大学的James Batteas教授和纽约城市大学Hunter学院的Charles DRAIN教授研究了分子的分子组装和电子传输特性，这可能有助于电子设备的小型化。摩尔定律在过去40年中一直有效，该定律指出，电子设备“芯片”上的晶体管密度将大约每两年翻一番，使电子设备变得更小、更快、更强大。一个紧迫的问题是，摩尔定律是否会延续到未来，或者它是否已经达到了它的根本极限。巴特阿斯和德雷恩教授研究了被称为类卟啉的金属有机化合物，这种化合物在自然界中被发现是血红蛋白和叶绿素的活性成分，以帮助这些发展。他们设计、合成和评估在表面组装成特定结构的卟啉类化合物的导电性能。使用原子力显微镜(AFM)和扫描隧道显微镜(STM)等成像技术，该团队可以将单个分子精确地放置在表面上，不仅在分子水平上测量它们的组装结构，还可以测量该结构如何控制电子在分子中的运动。这项研究具有更广泛的科学和技术影响，并使潜在的分子电子器件的合理设计成为可能，包括增强型光伏、化学传感器和分子电子学。该团队还培训学生在基础材料化学方面对教育产生更广泛的影响，为他们进入21世纪的高科技工作领域做好准备。巴特阿斯教授和德雷恩教授研究如何设计、合成和评估组装在金属表面的卟啉化合物的导电性能，着眼于实现用于光电子学应用的混合分子器件，包括增强型光伏、化学传感器和基于分子的电子学。强健的卟啉类化合物的电活性和自组装可以很容易地通过使用简单的高产率反应进行化学合成来调节，从而促进商业可行性，使它们成为有吸引力的靶标，作为电子设备中的活性元件集成。在这个项目中，通过纳米光刻和定向点击化学反应的组合，在金的精确结构的表面上组装了三氢呋喃类化合物，以产生横向尺寸小于10纳米的纳米组装。应用表征方法(时间分辨荧光法、紫外可见吸收法、扫描隧道显微镜和原子力显微镜)来了解小分子组装中局部分子相互作用如何影响电子传输性质，分子在表面的空间限制如何影响其最终的组装过程和可能形成的结构，以及组装结构如何控制电子传输。这项研究的更广泛影响提高了对卟啉类化合物的组装和电子传输性质的基本了解，并有可能影响分子电子器件和太阳能采光应用。通过教育和外展产生更广泛的影响，将原子尺度成像、纳米光刻、分子自组装和纳米电子学等工作的各个方面纳入小学生示范，作为为期一周的纳米技术夏令营的一部分(在德克萨斯农工大学)，并进入德克萨斯农工大学和纽约州立大学亨特学院的本科生和研究生课堂。

In this project funded by the Macromolecular, Supramolecular and Nanochemistry program of the Chemistry Division, Professor James Batteas of the Texas A & M University and Professor Charles Drain of Hunter College of the City University of New York study the molecular assembly and electron transport properties of molecules that might help in electronic device miniaturization. Moore's Law, which has held for the last four decades, states that the density of transistors on an electronic device "chip" will double approximately every two years, making electronic devices smaller, faster and more powerful. A pressing question is whether Moore's Law will continue into the future or has it reached its fundamental limits. Professors Batteas and Drain study metal-organic complexes known as porphyrinoids, found in nature as the active component of hemoglobin and chlorophyll, to aid in these developments. They design, synthesize and evaluate the conductive properties of porphyrinoids assembled into specific structures on surfaces. Using imaging techniques such as atomic force microscopy (AFM) and scanning tunneling microscopy (STM), the team can place individual molecules into precise arrangements on surfaces and measure not only their assembled structure at the molecular level but also how the structure controls the movement of electrons through the molecules. This research has broader impacts in science and technology, and enables the rational design of potential molecular electronic devices, including enhanced photovoltaics, chemical sensors and molecular electronics. The team also trains students, for broader impacts in education, in fundamental materials chemistry, preparing them for the 21st century high technology jobs sector. Professor Batteas and Professor Drain study how to design, synthesize and evaluate the conductive properties of porphyrinoids assembled on metal surfaces with an eye toward the implementation of hybrid molecular-based devices for photonics applications, including enhanced photovoltaics, chemical sensors and molecular based electronics. The electroactive properties and self-assembly of robust porphyrinoids can be readily tuned through chemical synthesis using simple high yield reactions that facilitate commercial viability, making them attractive targets to be integrated as active components in electronic devices. In this project porphryinoids are assembled on Au surfaces in precise architectures via a combination of nanolithography and directed click-chemical reactions to create nanoscopic assemblies of less than 10 nm in lateral dimension. Characterization methods (time resolved florescence, UV-visible absorption, STM and AFM) are applied to understand how local molecular interactions influence electron transport properties in small molecule assemblies, how spatial confinement of molecules on a surface influence their resulting assembly process and the structures that can be formed, and how the assembled architectures control electron transport. Broader impacts of the research result in an improved fundamental understanding of the assembly and electron transport properties of the porphryiods, with potential to influence molecular electronic device and solar light harvesting applications. Broader impacts through education and outreach incorporate aspects of the work, including atomic scale imaging, nanolithography, molecular self-assembly and nanoscale electronics, into demonstrations for elementary school students as part of a weeklong summer camp on Nanotechnology (at Texas A&M University), and into the undergraduate and graduate classrooms at Texas A&M University and CUNY Hunter College.