Collaborative Research: Directing Charge Transport in Hierarchical Molecular Assemblies

在这个由化学学部大分子、超分子和纳米化学项目资助的项目中，德克萨斯农工大学的James Batteas教授和纽约城市大学亨特学院的Charles Drain教授研究了分子的组装和电子传输特性，这可能有助于电子设备的小型化。摩尔定律在过去的四十年里一直有效，它指出，电子设备“芯片”上的晶体管密度大约每两年翻一番，使电子设备更小、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，或者它已经达到了基本极限。Batteas和Drain教授研究被称为卟啉的金属有机复合物，以帮助这些发展。卟啉在自然界中是血红蛋白和叶绿素的活性成分。他们设计、合成并评估在表面上组装成特定结构的卟啉类化合物的导电性能。利用原子力显微镜（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排列在表面上，不仅可以在分子水平上测量它们的组装结构，还可以测量结构如何控制电子通过分子的运动。这项研究在科学和技术方面具有更广泛的影响，并使合理设计潜在的分子电子器件成为可能，包括增强型光伏、化学传感器和分子电子学。该团队还为学生提供基础材料化学方面的培训，使他们为21世纪的高科技工作做好准备，从而在教育领域产生更广泛的影响。Batteas教授和Drain教授研究如何设计、合成和评估组装在金属表面的卟啉类化合物的导电性能，着眼于实现用于光子学应用的混合分子基器件，包括增强型光伏、化学传感器和分子基电子学。坚固的卟啉类化合物的电活性和自组装可以很容易地通过化学合成进行调整，使用简单的高收率反应，促进商业可行性，使它们成为电子设备中有吸引力的活性元件。在这个项目中，卟啉类物质通过纳米光刻和定向点击化学反应的结合，以精确的结构组装在金表面上，以创建横向尺寸小于10纳米的纳米级组装。表征方法（时间分辨荧光，紫外可见吸收，STM和AFM）被应用于了解局部分子相互作用如何影响小分子组装中的电子传输特性，表面上分子的空间限制如何影响其最终组装过程和可以形成的结构，以及组装的结构如何控制电子传输。该研究的广泛影响是提高了对卟啉类化合物的组装和电子传输特性的基本理解，并有可能影响分子电子器件和太阳能光收集的应用。通过教育和推广，包括原子尺度成像、纳米光刻、分子自组装和纳米电子学在内的更广泛的影响，作为为期一周的纳米技术夏令营（在德克萨斯农工大学）的一部分，为小学生演示，并进入德克萨斯农工大学和纽约市立大学亨特学院的本科生和研究生教室。

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.