基于应变石墨烯基底的有机分子薄膜溶液外延生长研究

Epitaxial Growth of Organic Molecular Films Through Solution Process on Strain Modified-Graphene Substrates

有机半导体器件中的载流子微观动力学行为受有机分子的吸附取向和排列结构的影响极大。因此,研究有机分子在衬底表面的堆栈行为对于促进高性能有机半导体器件的研究极为重要。石墨烯具有模板效应,可促进有机分子的有序堆栈,从而能极大地提高相应器件的性能。在π-π耦合相互作用驱使下,有机分子(通常具有平面芳香环结构)在石墨烯衬底上通常呈现“平躺”式吸附模式。如何克服有机分子在石墨烯基底上吸附取向的单一性是“石墨烯基有机器件”研究亟待解决的问题。本文提出一种利用石墨烯应变和空间微形貌协同调控有机分子吸附取向的新策略,在具有周期性纳米级弯曲结构的石墨烯上实现了具有直立分子取向的二维超薄C8-BTBT薄膜的外延生长。研究发现,石墨烯弯曲程度和应变共同决定了C8-BTBT分子的直立几何形状及其在石墨烯表面的定向生长。本研究为控制二维材料界面上的分子外延向功能异质结构方向发展提供了一种可行的途径。

In organic semiconductor devices,the micro dynamic behavior of charge carriers is greatly influenced by the adsorption direction and arrangement structure of organic molecules.Therefore,studying the stacking behavior of organic molecules on the substrate surface is extremely important for promoting the research of high-performance organic semiconductor devices.The template effect of Graphene promotes the orderly stacking of organic molecules,which greatly improves the performance of corresponding devices.Driven byπ-πcoupling interaction,organic molecules(usually with planar aromatic ring structure)usually exhibit a“flat”adsorption mode on graphene substrates.Breaking through the single adsorption orientation of organic molecules on graphene substrate is of great significance for expanding the application of graphene materials in the field of organic semiconductors.In this paper,a new strategy using graphene strain and spatial micromorphology to synergistically control the adsorption orientation of organic molecules is proposed.The epitaxial growth of two-dimensional ultrathin C8-BTBT films with vertical molecular orientation is realized on graphene with periodic nanoscale bending structure.It is found that the bending degree and strain of graphene jointly determine the vertical geometry of C8-BTBT molecule and its directional growth on the surface of graphene.This study provides a feasible approach for controlling the development of molecular epitaxy towards functional heterostructures at two-dimensional material interfaces.