固液界面二维共聚物生长的热力学与微区光电性质研究

2D copolymers are a group of graphene like materials, with its electron properties tunable by modifying the conjuncted structure. However, it is still a challenge to synthesize 2D copolymer with low defects and large area. It has been proven that the key leading to well long range ordered copolymer is to keep the surface reaction reversible. Therefore，it is extremely important to have a quantitative view of the thermodynamic parameters involved in the synthesis process. In this project, we will use the on-surface condensation of boronic acid and Schiff base reaction as model system, try to obtain a full quantitative view of all thermodynamic parameters based on a combination of experimental approaches and DFT simulations. By quantifying enthalpy and entropy of all involved states and processes, we can quantify the influence on the on-surface reactions brought by the solvent, the concentration of precursors and products, molar ratio of precursors and the temperature. In the end, we can find a theoretical way to predict the optimum parameters for interfacial growth of 2D copolymers. In the end, we will study the photoelectrical properties of the copolymer using home build Deep-ultraviolet Scanning Near-field Optics-Electrical Microscope with molecular resolution, which will provide important basis for applications in the area of photoelectrical devices.

二位共轭聚合物是一种类石墨烯材料，其电子性质可以通过改变分子的共轭结构来调节。目前，大面积生长高质量二维共轭聚合物依然很困难，其技术关键是保持反应的可逆性。因此，对每个物相热力学参数的定量研究极为重要。本项目以硼酸缩聚反应与席夫碱反应为研究体系，通过实验手段测定溶液相、晶体相的结合能，结合第一性原理计算得到的界面态结合能，对比理论计算得到的熵，定量研究溶剂、反应物与产物浓度、摩尔比、温度等对热力学参数的影响，以达到优化生长条件，大面积高质量生长二维共聚物的目的。并通过光辅助的扫描开尔文探针方法，以超高空间与时间分辨率研究光电性质与空间构型的关系，为二维共轭聚合物在光电器件领域的应用提供分子级别的依据。

以硼酸缩聚反应、氨化取代及N-Plasma氮化反应为研究体系，通过第一性原理及分子力学计算得到了二维共聚物及二维氮化物的形成能，对比理论计算得到的熵，研究了通过有机分子前体获得二维有机共聚物及二维氮化物的可能性及实验条件。研究了不同条件下获得的二维材料的结构与物理性质，为通过分子工程及原子工程的方法获得二维共价化合物进行了探索，生长大面积非晶二维共聚物、单晶二维氮化镓、二维InN及二维AlN，并通过AFM、STM、XPS及TEM进行了验证。