石墨烯/共轭聚合物纳米复合电存储器结构与性能调控及其电致阻变机理研究

Polymer resistive memory exhibits promising application in electronics and information fields. However, the lack of understanding in the electroresistant mechanism of polymeric materials has hindered the progress towards commercialization. Corelation between the intrinsic structure and the memory performance of polymers needs to be investigated based on the well-established model systems for better understanding their solid-state physics and electronics. In this proposal, nonvolatile memory devices based on graphene/conjugated polymer nanocomposites will be fabricated by constructing single-layer or multi-layer device structure, in which chemical modified graphene serves as the nano component with tunable energy level. Through carefully tuning in the electron-donor/acceptor natures and microstructures, as well as the energy band structure, effective interface action and transport behavior in nanocomposites could hopefully be achieved, which are critical factors for memory performance. The influence of electron-donor/acceptor nature, device structure, microphase morphology of polymer nanocomposites on the memory function and performance will be systematically studied in establishing a reasonable correlation between the intrinsic properties of polymer nanocomposite and the memory performance. Careful attentions will be paid to understand the essential process of electric induced charge transfer, trapping, and resistance change through the analysis of conduction mode and interface characteristics to elucidate the switching and conduction mechanism. Results of the proposed research works will provide theoretical basis for the materials design and the improvement in performance of polymer resistive memory.

聚合物电存储在电子、信息等领域有着巨大的应用前景和发展潜力，但对于聚合物材料的电致阻变起源及过程还缺乏本质的认识。系统设计模型体系，深入研究材料结构与存储性能的构效关系，是提高聚合物存储性能并实现其实用化的关键。本项目拟将化学修饰石墨烯作为可调能级结构的二维纳米组分，通过构筑单层和多层器件，来制备具有不同给受体性质、微相结构的石墨烯/共轭聚合物纳米复合电存储器，实现对聚合物复合体系的能带结构、界面作用、输运行为等影响器件性能关键因素的有效调控；研究复合体系給体受体性质、器件结构、微相尺寸对器件存储功能与性能的影响，探讨复合材料本征物性、结构与器件存储性能之间的内在联系，通过双稳态下的电流传输模式及两相界面特征分析，揭示聚合物复合体系中电致电荷转移、俘获、阻变的过程本质，阐明器件开关机理和导电机制，为高性能聚合物电存储器的材料设计和性能改善提供理论依据。

有机聚合物电存储在电子、信息等领域有着巨大的应用前景和发展潜力。尽管目前在材料探索和器件性能方面已取得显著进展，但是还缺少性能稳定、再现性好的器件，而且对于电致阻变起源还缺乏本质认识。本项目从制备可调控能级结构的非共价修饰石墨烯出发，合成了8种在水中稳定分散的化学修饰石墨烯，以及尺寸及带隙可调的氮化碳纳米片，对它们的形貌、尺寸、性能等进行了表征。上述材料单独作为活性层或与导电聚合物复合来制备夹层器件，发现有3种非共价修饰石墨烯表现出电存储性能（ON/OFF比<102）；而基于g-C3N4的器件ON/OFF比有所提高；磺化聚苯胺与氧化石墨烯复合体系表现出稳定的Flash存储性能，最大电流开关比达到104，响应时间仅为50ns。为了简化项目中提出的结构模型，得到综合性能优异的电存储材料，本项目设计了环糊精包含聚苯胺的微相结构，通过环糊精上的多羟基与聚苯胺分子链上氨基的氢键作用，来实现电场调控下的质子掺杂和去掺杂过程。形成的绝缘分子线结构能稳定分散于水中，方便旋涂制备夹层器件。该器件表现出优异的Flash性能，ON/OFF比可达108，同时还具有快的响应速度（300ns），好的擦写循环寿命，以及良好的环境稳定性。此外，还制备了聚合物钙钛矿及层状钙钛矿的电存储器件，通过改变聚合物含量及层状钙钛矿的层数，来调节有机钙钛矿的晶域尺寸、成膜性、缺陷密度以及载流子迁移途径等与电存储性能紧密相关的因素，从而来探讨材料本征物性、结构与器件存储性能之间的内在联系。这两种有机钙钛矿器件均表现出优良的电存储性能和环境稳定性，ON/OFF比可达105，而且在环境条件下保持60天无衰减。本项目制备的这些存储性能好、重现性和稳定性高的材料体系，还可用于微相结构界面分析，揭示体系中阻变的过程本质，阐明器件开关机理和导电机制，为后续的高性能电存储材料设计提供依据。