光调控D-A型超分子体系的电输运性质研究

Supramolecular assemblies with a designable donor-acceptor (D-A) architecture have attracted much interest motivated by the technological potential in applications such as artificial photosynthesis, solar energy conversion and storage, and organic electronics. Understanding and controlling the electron transport properties of supramolecular systems at single-molecule level is important for the development of optoelectronic materials and molecular devices. Although electron transport through a single molecule has been extensively studied, only preliminary progress has been made for supramolecular systems. There are still many problems to be solved, such as the relationship between the structure and the electronic properties, and the optical modulation on supramolecular conductance. Based on our previous research on electronic characterization of single molecular junction, we are devoted to study the electron transport properties in light responsive D-A supramolecular systems utilizing scanning tunneling microscopy break junction (STM-BJ) technique. In this project, we will firstly improve our existing STM-BJ system and develop the optics unit for optical modulated electron transport experiment. Secondly, based on the study of a model molecule, we explore the possible mechanism for the photoconductance in supramolecular systems combining theoretical calculations. Additionally, we plan to construct a general rule about the influence of chemical structure and bridge properties on the photoconductance among different supramolecular systems, providing experimental and theoretical foundation for the design and construction of organic optoelectronic materials and devices.

D-A（Donor-Acceptor）型超分子可以实现高效率的光致电子转移，具有可设计的功能特性，在光合作用、太阳能电池和有机电子学等领域中受到广泛关注。利用基于单分子电导测量的电学方法研究超分子体系的电输运性质，有助于从分子水平理解光电现象。目前，单分子电输运性质研究已取得较好的发展，但超分子体系的研究尚处于起步阶段，仍有很多关键问题亟待解决，如：超分子结构与电输运性质的构效关系不够清晰，对超分子电导的光调控尚待实现等。本项目将以D-A型超分子为研究对象，通过扫描隧道显微镜裂结（STM-BJ）技术在单分子水平研究并调控超分子体系的电输运性质，力求解析光调控超分子电导的物理机制，并揭示组分化学结构和桥键性质影响超分子光电导的一般规律。本项目研究既是分子电子学的基本研究内容，又与超分子化学、材料科学等领域有着较强的学科交叉性，将有望为有机光电功能材料与器件的设计开发提供相应的科学基础。

理解芳香性有机分子化学结构和电子输运性质之间的构效关系，从而调控其电学性质，对未来设计和构筑单分子及超分子光电器件具有重要意义。项目研究组建立了高灵敏度且稳定可靠的扫描隧道显微镜断裂结（STM-BJ）装置，实现了在单分子尺度上对目标分子的电学性质进行原位表征；系统探究了取代基对三聚茚等芳香性分子量子干涉效应的影响，探究了分子-电极界面对于富勒烯类分子电导的影响规律，从单分子水平研究了具有含碳纳米管段内嵌金属富勒烯的电子输运性质，通过化学反应实现了对于单分子器件电导的原位调控，并结合理论计算解析了分子电子输运的规律和机理。进一步基于分子间弱相互作用构筑了组装型分子器件，研究了由给体（Donor）和受体（Acceptor）结构基元形成的超分子自组装体的电子输运行为。此外，还进一步构筑了规则且统一的图案化分子自组装线性阵列，研究了桥联结构对于分子自组装过程和晶体结构的影响机制，在纳米尺度上考察了线性阵列的光电性质。本项目为进一步在原子分子水平上开展有机光电器件的研究工作奠定基础。. 项目负责人以（共同）第一作者及通讯作者发表SCI论文3篇，包括J. Am. Chem. Soc.、ACS Appl. Mater. Interfaces、Chem. Comm.，并有项目研究成果近期被Angew. Chem. Int. Ed.接收（1篇），按期完成了各项研究任务。