Controlling Charge Transport of Organic Semiconductors and Molecules via Edge-On Gating Effect

本项目致力于模型分子晶体管的合成及其物理性能的研究。这项研究有助于为电子系统小型化所面临的限制找到答案。这些分子体系的合成方法被证明是可行的，单分子的电学测量技术也是可行的。初步结果表明，适当的化学功能可以开关电流，类似于晶体管的功能。在材料研究部固态和材料化学项目的支持下，该研究团队正在进行广泛的合成努力，以制备一系列具有不同结构和功能的新化合物。理论研究是为了计算和理解分子的电学性质。该项目为学生提供了一个很好的教育平台，特别是一个有效的孵化器，鼓励少数民族学生走上科学研究的职业道路。该项目包括招收这些学生的计划。这项拟议的工作是一项综合了化学、材料科学、物理和纳米科学以探索新的科学和材料的跨学科努力，需要在合成方法和现代表征技术的应用方面进行广泛的创新，以深入了解分子材料的电子性质。因此，它为学生提供了广泛的研究和教育机会。在这个项目中工作的学生获得必要的知识和培训，成为未来有机/材料化学和有机电子材料领域的领导者。新材料的产生可能会对电子工业产生潜在的影响。技术摘要本项目旨在合成基于环番构筑基元的模型分子晶体管，并研究边缘化学门控对半导体分子和材料电子性质的影响。环番部分含有一个垂直的吡啶单元，该单元与带有两个乙烯基团的共轭半导体分子相连。因此，吡啶环中的pi-体系与半导体线中的pi-体系是垂直的。栅极端不与半导体实体直接共轭，非常类似于FET中的栅电极。开发的分子系统类似于场效应晶体管，但允许使用断裂结扫描隧道光谱技术来研究门控效应。研究的重点是边向化学门控效应，通过在垂直的吡啶环的对位引入各种不同电子性质的官能团。这些取代基的行为类似于施加的门控电压，允许进行详细的物理研究，以深入了解控制电荷传输的过程。该项目致力于广泛的合成努力，以制备一系列具有不同门控部分、共轭长度和电子性质的新化合物。该团队建立了一套扫描隧道光谱系统来表征分子的电荷传输行为，包括单分子电导、电子隧道势垒和化学门与官能团的关联。理论研究有助于计算和理解门控吡啶部分的电荷密度变化，这是一个与电荷输运电导相关的参数。对门控效应的可能应用进行了探索，包括质子触发开关和光致开关

Non-technical AbstractThis project is focused on synthesis of model molecular transistors and investigation of their physical properties. The research can help to find answers for the limitations faced in miniaturization of electronic systems. Synthetic approaches to these molecular systems are shown to be feasible and techniques for electric measurements on single molecules are operational. Preliminary results indicate proper chemical functions can switch electric current on and off, similar to functioning of transistors. With support from the Solid State and Materials Chemistry program in the Division of Materials Research, this research team is pursuing extensive synthetic efforts to prepare a series of new compounds with different structures and functions. Theoretical studies are performed to calculate and understand the electric properties of molecules. This project provides an excellent educational platform for students, especially an effective incubator to encourage minority students into a career path of scientific research. This project includes a plan for recruiting these students. The proposed work is an interdisciplinary effort that integrates chemistry, materials science, physics and nanoscience to explore new science and materials, and requires extensive innovations in synthetic approaches and applications of modern characterization techniques to gain insight into the electronic properties of molecular materials. It thus offers a broad spectrum of research and educational opportunities for students. Students working in this program gain necessary knowledge and training to be future leaders in the area of organic/material chemistry and organic electronic materials. New materials generated can have potential impact on electronic industries.Technical AbstractThis project is aimed at synthesis of model molecular transistors based on cyclophane building motif, and investigating the edge-on chemical gating effect on electronic properties of semiconducting molecules and materials. The cyclophane moiety contains a perpendicular pyridine unit that is connected to the conjugated semiconducting molecules with two vinyl groups. Thus, the pi-system in pyridine ring is orthogonal to that in semiconducting wire. The gating end is not directly conjugated with the semiconducting entity, closely resembling a gate electrode in FET. The molecular system developed resembles a field effect transistor, but allows using break-junction Scanning Tunneling Spectroscopy techniques to investigate the gating effect. The research effort is focused on edge-on chemical gating effect, by which various functional groups with different electronic properties are introduced to the para-position of the perpendicular pyridine ring. These substituents behave like applied gating voltage, allowing for detailed physical investigation to gain insight into in controlling charge transport. This project devotes extensive synthetic efforts to prepare a series of new compounds with different gating moieties, conjugation lengths, and electronic properties. This team has set up a Scanning Tunneling Spectroscopy system to characterize the charge transport behavior of molecules, which include single molecular conductance, electron tunneling barriers and chemical gating correlation with functional groups. Theoretical studies help to calculate and understand the charge density changes in the gating pyridine moiety, which was shown to be a parameter correlated to the charge transport conductance. Ideas for possible applications of the gating effect are pursued, including proton triggered switch and photoinduced switch