透明柔性铜纳米线弯曲疲劳寿命及传导性质的研究

In micro-nano scale, repeated bending working condition, flexible Cu nanowires has emerged a lot of failure forms, leading to its conductivity attenuation. The bending life and conduction properties of the copper nanowires are usually met with in the course of replacing ITO for flexible displays and solar cells, and thus are widely concerned and regarded as a basic sicientific issue. In the light of the simulation fact of the changes in bending stress and quantum conduction of Cu nanowires by different configurations, as well as triune relationship of bending stress - conduction - the structural evolution, we proposed in this project an academic thought of the bending properties regulation by size and configurations to reduce the cost and improve the properties. We could receive the structure, atom and the electron distribution of copper nanowires by First-priniciple simulation. The effect of bending stress on atom structure, electrical structure and conduction properties is investigated, and then the structure and size parameters of the copper nanowires can be optimized. The mechanism of bending failure and conductivity attenuation is revealed and the key factor can be found out. The conduction properties as bending processing could be received in situ bending experiments on single nanowire by PI95 transmission electron microscopy combined with mechanical properties tester. Comprehensive utilization of test equipment (PI95) and first-principles calculation, The cycles of experiment - simulation - experimental are repeated, and to explore the physical nature of the conduction properties from atomic and electronic scale.The research results will expand the application of copper nanowires, which is of stable structure, high conductivity and flexible, may be a good candicate for flexible solar panel, flexible display in the future.

铜纳米线取代ITO用于柔性显示器和太阳能电池时，其弯曲寿命和传导性质是经常涉及且受关注的基础科学问题。本项目基于构型改变铜纳米线弯曲应力、传导行为的模拟事实以及弯曲应力-传导-结构演变三位一体的构架关系，提出利用结构和尺寸调控其弯曲寿命的学术思想，调控成本和性能。通过模拟获取材料结构、原子、电子的分布状况，获得铜纳米线结构、耐弯曲性质和传导之间的关系，阐明构型对材料结构失效、传导性质下降及耐弯曲性能的影响规律,为实现传导和耐弯曲性能调控提供理论依据。并利用PI95透射电镜联用力学性能测试仪对单根纳米线进行原位弯曲实验，在弯曲应力作用的同时得到电导率。综合利用透射电镜联用力学设备(PI95)和第一原理计算，进行实验-模拟循环优化，从原子和电子量级对传导性质的物理本质进行探讨，获取柔性铜纳米线材料的电子结构和传导性能等信息。研究成果将为其在未来柔性太阳能、显示器的应用提供良好的理论基础。

由于铜纳米线比ITO具有更好的耐弯曲性能，以及更低的价格，有望取代ITO用于柔性显示器和太阳能电池时，其弯曲寿命和传导性质是经常涉及且受关注的基础科学问题。本项目采用第一原理密度泛函方法研究了弯曲应力对铜纳米线、传导行为的影响，通过调节原子结构、尺寸参数来提高其传导性能，获得了在弯曲作用下铜纳米线的电子态密度图，观察电子分布如何随弯曲强度变化。通过得到的部分态密度图，分析弯曲应力对各个电子层的影响，阐明弯曲应力作用下铜纳米线微结构的内在演化机制，揭示弯曲应力、结构、尺寸与传导性质之间的内在联系.通过实验方法完成铜纳米线的制备进行原位弯曲实验。通过与拉伸、压缩等单向应力作用下行为的比较，探讨了造成铜纳米线在弯曲下不同行为的微观机理并探索其弯曲疲劳的主控因素。结果证明非螺旋形结构纳米线在加电场之后量子导电通道数减少，而螺旋形结构纳米线在加电场之后量子导电通道数增加。同时，螺旋型纳米线在1 V/Å，2.5nN时传导率最好，比直线型能够承受更多的应力，更适合作为透明柔性材料。