石墨烯调控导电聚合物分子的界面效应与输运性质的研究

Due to the excellent structures and properties, graphene(G)/graphene oxide (GO) has been chosen as one of the main materials to build polymer-based devices to improve the efficiency and stability by making use of the interactions between G/GO and poly(3-alkylthiophene)(P3AT), which has been one of the hot research topic currently. Recently, devices with GO/G working as electric acceptor, hole transport layer and electrode etc. have been explored. However, the results are challenging, since it was found that the performance of such device is no better than those without G/GO. Based on this fact, this project is designed to understand the molecular mechanism of the interactions between P3AT and G/GO by using scanning tunneling microscopy/scanning tunneling spectroscopy (STM/STS) combined with the theory calculation. Then the effect of addition of GO on the structures and morphophy of the film will be studied further and discussed in detail. The purpose of this project is to understand how the G/GO affects the interfacial structures and properties of P3AT from three levels: interaction mechanism at molecular level - - the structures and morphophy at micro/nano level- - the transport properties of the devices. And also the effects of the content of GO, layer number and annealing etc. on the structures and properties of the P3AT will also be investigated. These results will provide theoretical and experimental supports for the improvement of the device's performance based on the G/GO and conducting polymer in future.

石墨烯具有优异的结构和物理化学性质，以石墨烯作为半导体器件的构筑材料之一，利用石墨烯与聚3-烷基噻吩（P3AT）之间的相互作用，有效提高基于P3AT器件的效率和稳定性是当前研究热点之一。近年来，人们构筑了以石墨烯为受体材料、空穴传输层以及电极材料等器件，但这些器件效率并未见明显提高，甚至有时会有所降低。针对这种情况，本项目拟首先利用扫描隧道显微镜/扫描隧道谱（STM/STS）研究石墨烯与P3AT界面相互作用的分子机制，然后考察石墨烯对P3AT界面聚集行为和输运性质的调控。试图从分子水平作用机制- - 微纳尺度聚集结构- - 器件输运性质三个层次上理解石墨烯如何对P3AT的界面结构和性质实现调控，并系统研究不同条件下（内因：石墨烯含量，层数等；外因：溶剂、退火等）石墨烯对P3AT界面组装及输运性质的调控，为提高基于石墨烯和导电聚合物器件的效率提供理论依据和实验支持。

聚（3-己基噻吩）（P3HT）作为一种半结晶性高分子，其已经成为太阳能电池、有机场效应晶体管等电子器件中使用最多、效果最好的导电聚合物之一，其聚集行为、组装形貌等已经得到大量的研究。石墨烯具有优异的结构和物理化学性质，以石墨烯作为半导体器件的构筑材料之一。利用石墨烯与P3HT之间的相互作用，有效提高基于P3HT器件的效率和稳定性是当前研究热点之一。本项目中，我们首先以P3HT为研究对象，主要从两个方面对其与GO之间的相互作用进行了研究：首次，从亚分子水平上直接观察并总结了在外界驱动下（热退火）单分子链构型的变化规律，并进一步研究了分子链间聚集行为以及与氧化石墨烯之间相互作用随着热退火的变化情况。从单个P3HT分子链到P3HT聚集体以及聚集体与GO之间的相互作用上详细阐述了外界条件对导电高分子构型、组装以及给受体间相互作用的影响。这对于我们掌握影响器件效率的本质因素、如何有效地提高器件效率提供了重要的实验数据。. 另外，我们将扫描探针显微镜与光谱技术相结合，系统地考察了具有不同纳米结构的P3HT纳米纤维与GO之间的相互作用。通过实验我们发现在固液界面上具有较低分子链有序度的P3HT纤维在GO表面上共轭长度会进一步增加。而且GO与不同纳米结构的P3HT纳米纤维之间的会发生不同的掺杂，开尔文探针力显微镜结果也表明与GO发生相互作用后P3HT的表面电势也发生变化。这一研究结果对我们构筑具有更高性能的期间提供了非常有价值的信息。