三苯胺类共轭高分子功能材料的制备及其电致电阻特性研究

With the research and development of high-performance resistive-switching organic functional polymers, the realization of resistive random access memory with low-cost, low-power consumption, high-speed, high-storage density and high-reliability is of profound importance for the information storage technology. To date, polymer resistive-switching materials have attracted tremendous amount of attentions, though some key factors employed to evaluate the performance of RRAM devices, such as the retention ability, number of write-read-rewrite-read (WRER) cycles as well as the uniformity of operating parameters, are still of necessarity for a further improvement. In this project, we are going to design and synthesize novel triphenylamine-based redox-active conjugated copolymers, and to investigate the effect of chemical structure, molecular configuration, molar content as well as spatial arrangement of the triphenylamine unities on the modulation of the electrochemical redox behavior and electrical transport properties of the polymer materials. With the space-resolved spectroscopic techniques, it is possible to monitor the changes of the redox states of the triphenylamine unities or concentration/distribution of the formed polarons during the electrical transition process, for a better understanding of the relationship between the resistive- switching phenomena and the electrochemical behavior, and a more clear identification of the key issue influencing the charge transport properties of the conjugated copolymers. By using viologen as the counter-acting material to fabricate heterojunction structures with balanced charges in the redox-system, the stability and reliability of the resistive-switching properties of the triphenylamine-based conjugated copolymers will be effectively enhanced. With this project we are aming to provide both theoretical and experimental support for the future implementation of novel polymer-based information storage devices.

研究和开发具有优良电致电阻效应的功能高分子材料，实现具有低成本、低功耗、高速、高密度和高可靠性等优点的电阻式随机存储器，对于信息技术领域的发展具有重要的意义。如何提高阻变响应速度、保持时间、读写循环次数、各转变参数的均一性等一些衡量器件性能的关键指标参数仍是当前制约高分子阻变随机存储器发展的瓶颈之一。为解决这些问题，本项目拟设计、合成具有氧化还原活性的三苯胺类共轭高分子功能材料，通过电化学氧化还原作用实现电致电阻效应；澄清三苯胺结构单元的种类、构象、在分子链中的相对含量与空间分布等因素对其电化学行为及输运特性的调控作用；利用光谱分辨技术检测阻变过程中三苯胺基团的氧化态或极化子的浓度与分布的变化，阐明电致电阻效应与材料的电化学行为之间的关联规律，揭示影响电荷输运特性的关键因素；制备高分子-紫罗精氧化还原异质结构，获得具有稳定电致电阻效应的高分子阻变体系，为设计新型高分子信息存储器件提供参考。

高分子阻变随机存储器是一种新兴的存储技术，具有成本低、重量轻、易加工、可以大面积制作、可制备柔性电路、与现有CMOS工艺兼容等的优点，且可以通过分子设计与可控制备对其电荷输运特性进行有效调控，进而在分子尺度上“定制”存储器件并实现海量存储。本项目开展三苯胺类共轭高分子功能材料的制备及其电致电阻特性调控的研究，主要通过分子模拟与化学合成方法的控制，设计制备了一系列具有三苯胺电子给体和噁二唑电子受体基团的乙烯基非共轭高分子材料；通过系统研究三苯胺基团的类型、在分子链中的相对含量和链接方式等因素对其电化学行为（多级氧化还原、Redox起始电压、分子轨道能级、循环稳定性）及电致电阻效应（阻变置位/复位电压、多态转变、开关比）的调控作用，发现高分子材料的分子构型能够显著改善其阻变型能，澄清了氧化还原作用与材料电荷输运特性的关联规律，揭示了影响材料阻变特性的关键因素，获得具有稳定电致电阻效应的三苯胺类高分子阻变材料体系；阐明了柔性阻变存储器的机械失效机制，开发了有机-无机杂化阻变材料，有效提高了器件的存储性能和机械性能，为开发新型高分子信息存储器件提供参考。