基于聚酰亚胺的电学记忆效应及数据存储研究

Polymers tend to present better mechanical properties. Instead of expensive fabrication equipment that vacuum evaporation of organic material onto a silicon wafer, manufacturers could eventually use ink-jet printers or spin-coating to spray liquid polymer circuits onto a surface. Furthermore, the polymer memory cells can be stacked to produce a three-dimensional structure. The main issue of polymer materials is temperature stability, most of common polymer materials can not withstand, for instance, the CMOS back end of line (BEOL) processing. To date, only a few polymeric materials including PEDOT, PAA, PAN and polypyrrole can be used for memory devices. Most of them are as a matrix of a dye, CT-complex or gold nano-particles in a doping system. Doping and solution casting, however, do not always give rise to uniformly dispersed dopants, and thus, can result in phase separation and ion aggregation, which are detrimental to the performance of a memory device. The design and synthesis of a stable polymer that can provide the desired electronic properties with improved mechanical characteristics is the strategy chosen to overcome the above-mentioned difficulties. The project includes two parts, .(1) Synthesis and characterization of a series of processable polyimide derivatives and their metal complexes that can provide the required electronic properties for memories and still possesses good thermal, chemical and mechanical stabilities..(2).Nano- or micro-pattern electrode surface for performance improvement of memory devices. Fabrication of plastic memories based on these self-assembled and spin-coating films. Characterization of the memory effects and evaluation of device performance. Developing new packaging technology for the capsulation of high-performance devices at low temperature.

聚酰亚胺是综合性能最佳的有机高分子材料之一，耐高温达 400℃以上，被广泛应用于电子信息领域。本项目拟设计并合成出一系列具有电存储效应的、兼有整流效应的或热稳定性良好的聚酰亚胺类电活性聚合物；制得具备响应速度快、低读/写电压、高"0" 与"1" 信号比及稳定性良好的聚合物电存储器件，揭示不同有机半导体材料组成及器件制作工艺对器件性能的影响规律；研究并解决电存储单元集成为交叉存储阵列或TFT存储阵列时在材料、器件及技术方面存在的问题，探索低温封装技术；以理论计算与实验测试相结合，阐明聚合物电存储器件的工作原理及电荷传输机制。该项目拓展聚酰亚胺电子材料在信息存储方面的应用研究，不仅在新存储技术发展上有重要的科学意义，而且一旦技术成熟，将具有广阔的应用前景。

在基金委主任专项基金的支持下，本项目按计划完成了前期的研究内容。合成了5个含有富电子或缺电子基团的双功能合一的可组装成高分子的有机单体；利用Suzuki偶合反应等方式将这些有机单体共聚获得一系列结构确定、分子量高、溶解性良好的大分子化合物即为电子推（给体）-拉结构（受体）的聚合物存储材料；采用各种现代分析方法，测得这些新型聚合物存储材料的物理性能、电化学性能。通过在各功能团引入长的烷基连来提高大分子的溶解性，使得这类聚合物电存储材料能溶于二氯甲烷、甲苯、二甲苯等常用的有机溶剂，并可采用溶液法旋涂成膜，制备均匀有机薄膜。通过改变受体马来酰亚胺上取代基和给体的种类来调节聚合物材料的电子效应，从而改善聚合物的载流子传输性能；在功能基团中引入苄基来控制分子良好的平面堆砌从而可以大大提高薄膜的电荷传输能力。我们以马来酰亚胺为核，以噻吩为取代基，设计并合成了一系列人字形结构的二噻吩马来酰亚胺材料，实验发现，这些分子都表现出多种不同聚集方式（J/H型，π-stacking/slipping型）的稳态结构。其中，TMI具有五种不同荧光的聚集态结构，在外部刺激下可以实现五态和on/off的可逆开关，是目前文献报道最简单的多重刺激响应材料，在多级存储中具有重要的应用前景。