多孔聚合物电介体的设计、合成及其有机晶体管存储器

It is of great importance to design and develop novel polymer electret materials for achieving highly stable and high-performance organic field-effect transistor memory elements and their flexible devices in the big data era. The performance of memory devices with many linear polymers based on polystyrene or polyimide or their derivatives as electret are not excellent enough. On the other hand, these polymer electrets exhibit an unsatisfactory thermal stability and/or multi-step synthesis. Moreover, the relationships between the molecular structure of polymer electret and the performance of transistor memory and the operation mechanism are not quite so clear owing to lack of comprehensive study. Based on previous studies and our early work, this project aims to develop solution processible and pi-conjugation-interrupted porous organic polymer electrets with excellent thermal stability via concise metal-free catalytic friedel-crafts crosslinking polymerization for transistor memory elements. The memory characteristics can be effectively tuned by the porous structure of polymer electret, which is also beneficial to improve the mechanical stability of the flexible memory devices based on the corresponding polymer composite electrets. The electronic energy levels of the polymer electrets can be tuned via p-n energy band tuning theory and other electronic donors or acceptors can be introduced into the porous structure. The effect of the field-induced intramolecular or intermolecular electron transfer on the memory characteristics will be also investigated. Furthermore, this project also aims to uncover the relationships between the molecular structure of polymer electret and the performance of transistor memory and the operation mechanism. This project will hopefully not only provide new ideas for designing high-performance polymer electrets, but also offer effective technical support for their industrial applications in the future.

设计开发新型聚合物电介体材料对获得稳定高效的有机场效应晶体管存储器及其柔性器件具有重大意义。许多基于聚苯乙烯及其衍生物的线性聚合物或聚酰亚胺类电介体的存储性能欠佳，且其热稳定较差或合成路线复杂。聚合物电介体与存储性能参数的构效关系和存储机制也很不明晰，缺乏细致研究。根据文献调研和相关工作基础，本项目拟通过简单、无金属催化的傅克交联聚合合成热稳定性良好和可溶液加工的共轭打断的有机多孔聚合物。多孔结构的引入能有效地调控存储器件性能和提高基于复合电介体材料的柔性器件的机械稳定性。拟通过p-n能带调控理论调节聚合物的电子能级和将其他电子给体或受体等功能分子引入聚合物的孔结构，考察场诱导的分子内或分子间的电子转移对晶体管器件存储性能的影响，并研究和阐明电介体结构与存储性能之间的构效关系和存储机制。该研究有望为设计高效电介体材料提供借鉴思路，并为该类电介体的实用化提供技术支持。

设计开发新型有机/聚合物电介体材料对获得稳定高效的有机场效应晶体管存储器及其柔性器件具有重大意义。本项目围绕着二芳基芴类电介体材料展开，设计并利用芴基叔醇的傅克反应合成了一系列孔状芴基纳米格子、芴基功能化的堆积聚合物和芴基多孔聚合物电介体材料，并考察了其有机晶体管存储器件性能。比较了芴基孔状风车格一锅法和多步法的合成路线，获得了高产率的风车格WG3和WG4。通过旋涂法制备得到WG3纳米阵列，以其作为电介体材料研制出非易失性有机晶体管存储器件，表现出较大的存储窗口（＞ 40 V），较快的开关速度（≈ 1 s），稳定的保持能力（> 104 s）和可靠的开关特性。PVK类堆积聚合物的位阻功能化能显著提高其有机晶体管存储器的开关比、存储窗口和器件稳定性，可能的原因是堆积聚合物的局部堆积态结构能起到捕获电荷的作用，且位阻化堆积能增强电荷的捕获存储。在上述基础上，利用芴基叔醇的傅克反应聚合得到了一系列可溶芴基多孔聚合物，聚合物具有较大的比表面积（450 m2/g）和优异的热稳定性（536℃），其有机晶体管存储器表现出较大的存储窗口（45 V）、开关比（106）和维持时间（> 104 s）。上述研究表明二芳基芴类小分子、堆积聚合物和多孔聚合物等电介体材料在有机晶体管存储器中具有良好的应用前景、对其他电介体材料的设计合成具有重要借鉴意义。