单分子层分子晶体可控组装与电荷传输机制研究

Self-assembly of a monolayer of molecules on dielectric surfaces is a promising approach for the development of molecular devices proposed in the 1970s. Recently, monolayer molecular crystals (MMCs) have been demonstrated as an alternative route for overcoming the mobility limitation of substrate chemically bonded self-assembled monolayers (SAMs). However, the difficulty in scale up monolayer domain, lack of n-type counterpart and growth limitation on inorganic substrates have prohibited advantages of MMCs in charge transport studies and sophisticated optoelectronic applications. We will be investigating, in particular, how the design of the conjugated molecular core and the side chain substitution impacts its two-dimensional assembly. We are planning to develop series of new methods for bottom-up growth of large-area MMCs. To understand the physical nature of the charge transport in the MMCs, the temperature dependence of mobility will also be studied. The optical charge modulation spectroscopy (CMS) will be employed to avoid external disturbances such as the method of mobility extraction or the contact effects. We wish to develop a fundamental understanding of structure-property relationships in MMCs, to establish design guidelines for the next significant leap in semiconductor performance.

发展自组装单分子层是实现上世纪70年代提出的分子器件的一种重要途径。早期主要通过与基板共价键形成的自组装单分子层（SAMs）来制备分子器件，典型的是单分子层晶体管。最近，单分子层分子晶体（MMCs）也被证实是构筑单分子层晶体管的另一种有效方案，并能克服前者较低迁移率的限制。然而，MMCs难以大面积生长，n型材料的缺乏，仅能在无机基板上生长等都限制了其在电荷输运机理研究和复杂光电器件方面的应用优势。因此，我们将探索共轭分子核以及其侧链功能团对分子二维生长的影响，发展自下而上分子组装新方法实现MMCs的大面积制备，研究迁移率与温度变化的关系，利用微区电荷调制光谱（CMS），结合理论计算来理解MMCs中分子结构与性能之间的关系，揭示电荷输运的物理特性，为有机半导体性能下一个跨越式发展提供指导。

单分子层分子晶体 FET 拥有均一厚度的半导体层、避免了体电阻的存在以及暴露出的导电沟道传输层，为揭示有机半导体材料本征性能以及本征的温度迁移率关系、理解载流子传输模式、构筑均一性器件阵列和大规模集成应用提供了重要机遇。然而，单分子层分子晶体难以大面积均一厚度生长，物理化学性能表征和高性能器件构筑手段不足等都限制了其在电荷输运机理研究和复杂光电器件方面的应用优势。本项目聚焦单分子层晶体材料的输运机制和高性能器件与电路应用，通过创制新分子材料实现了高质量单分子层晶体的可控制备，融合原位器件测试装备搭建构建了低缺陷、低接触电阻高性能单分子层晶体器件，揭示了电荷输运的机制，并推动了单分子层电路应用。