电场诱导调控共轭高分子薄膜形貌机理研究

The purpose of this proposal is to study the mechanism and dynamic processes of the morphology control of conjugated polymers under electric field. Based on the preliminary studies, P3HT and several typical low-band-gap conjugated polymers (CPs) will be the object of this study, characterization methods including spectroscopy and topography measure will be utilized to explore the effect of many factors (such as crystallization, orientation, morphology control, etc.) on the molecular structure in conjugated polymer, electric-field strength, operation time, temperature, solvent and other conditions will be studied, in order to obtain the relationship between both of them and reveal the internal rules. Density functional theory and molecular simulation methods will be exploited as research methods to establish the interaction model of conjugated polymer under electric field, in order to reveal the response mechanism and dynamic processes of conjugated polymer under electric-field, which can be used for the photosensitive layer morphological control in polymer solar cells. The accurate creation of phase separation morphology with optimized structure in photosensitive layer film will significantly improve the performance of the resultant photovoltaic device. Electric-field-induced method is very easy to operate, pollution-free, and convenient control. The understanding of morphology control mechanism developed in this proposal will not only benefit for high-performance photovoltaic cells, but also have broad application prospects and important research significance in the field of organic thin film transistors and polymer morphology studies.

本项目旨在探索电场诱导作用下，共轭高分子在薄膜中形貌调控的机理及动力学过程。在已有的前期研究工作基础上，以P3HT及几种典型的窄带隙共轭聚合物为研究对象，通过光谱学、形貌学等表征手段, 探索共轭聚合物分子结构、电场强度、作用时间、温度、溶剂等条件与共轭聚合物在薄膜中结晶、取向及形貌调控之间的关系，揭示其内在规律；以分子轨道理论和密度泛函理论为研究方法，建立共轭高分子在外电场下的作用模型，研究共轭高分子在电场效应下的响应机理及动力学过程，以用于指导电场诱导方法精确调控有机聚合物太阳电池光敏层形貌，在薄膜中构建具有优化结构的相分离形态，提高光伏器件的性能。电场诱导方法操作简单、无污染、易于控制，用该方法调控共轭高分子薄膜形貌的研究，不仅对制备高性能聚合物光伏电池有着广阔的应用前景，同时对有机薄膜晶体管，高分子形态学研究等领域都有着广泛的应用前景和重要的研究意义。

共轭高分子在薄膜中的形貌直接影响了器件的综合性能。本项目以P3HT和几种常见的共轭高分子为研究对象，研究了电场诱导方法在调控共轭高分子在薄膜中结晶，取向及聚集形态调控上的作用规律，通过密度泛函理论，建立了共轭高分子在电场下的作用模型，将实验数据与理论计算相结合，得出了最优化的薄膜形貌控制条件。根据以上的理论指导，我们首次利用电场诱导技术调控P3HT/PMMA复合膜体系的形貌，成功实现了P3HT与PMMA在电场作用下形成自发相分离形态，得到了最优化的半导体/绝缘体两相接触界面，该方法可以广泛用于提高薄膜晶体管性能。另外，我们利用电场诱导层层组装方法，采用共轭高分子单一组分的交替沉积，成功制备了高质量，高结晶度的共轭高分子薄膜，可以在分子水平上精确控制薄膜的厚度和组成，重要的是该方法对有机共轭高分子制备薄膜具有普适性。基于以上对电场与有机半导体之间作用关系的理解，结合超分子组装作用，将氧化石墨烯与金属纳米粒子及共轭小分子在电场驱动下自组装成膜，该复合材料具有超快的湿敏响应和NO2气敏响应性能，同时具有优异的自恢复性能。该项目揭示了电场在共轭高分子及小分子薄膜聚集形态调控的规律和机理，为该技术在其它更多领域的应用奠定了基础。