ITO薄膜/柔性基底的断裂与脱层失效行为实验研究

Indium tin oxide (ITO) films are preferred as the anodes of flexible displays due to its good conductivity and light transmittance. However, fracture and delaminating always happen, because of the stiff and brittle properties. The fracture and delamination behavior of the indium tin oxide (ITO) thin films on flexible substrate are investigated in this project. And the scanning electron microscope (SEM) is combined with the gratings based measurement methods, to realize in-situ observation and measurement of the fracture and delaminating behavior of the ITO films. Micro-scale in-situ tensile test system is established. And high-quality and high-frequency gratings fabricating techniques on thin films are developed, to realize the in-situ full-field in-plane/out-of-plane deformation measurement of the ITO films. At the same time, the appearance, growth and propagation of cracks of the ITO films and interface can be characterized quantitatively. The evolutive relationship between the fracture and the buckling-driven delaminating of the ITO films is to be established. Hereby the failure mechanism of ITO films is to be revealed. The results are to provide instructions to the parameter optimization during the fabricating of the ITO films.

ITO薄膜具有良好的导电率、透光率，在柔性显示领域是一种首选的电极材料。然而由于硬而脆的力学特性，ITO薄膜在柔性基底表面往往易发生断裂、脱层的失效行为。本项目拟采用扫描电子显微镜（SEM）结合光栅测量方法，对氧化铟锡薄膜（ITO）/柔性基底的失效行为进行研究，以解决ITO薄膜微观损伤的原位观察、测量的技术难题。通过搭建微尺度原位加载测量系统，发展ITO薄膜表面高质量、高频率光栅的制备方法，实现微观尺度ITO薄膜的面内、离面变形全场在线定量测量，以及对薄膜的裂纹和薄膜/基底界面间的缺陷萌生、生长和扩展的定量表征。以此建立ITO薄膜断裂与脱层屈曲之间的演化关联，揭示ITO薄膜的损伤失效机制，为ITO制备工艺的参数优化提供指导。

ITO薄膜是柔性显示领域的基础材料，在ITO薄膜材料服役过程中，断裂、脱层等失效行为不可避免。本项目采用实验和理论分析的方法对 ITO 薄膜/柔性基底的断裂、屈曲脱层的失效行为进行了研究。首先设计了一套微尺度薄膜加载测试系统，搭建了薄膜原位加载观察测试系统，对系统的灵敏度和可靠性进行了测试分析，实现了对薄膜/基底结构表面变形和损伤演化的定量表征；其次对薄膜三维形貌和变形特性进行理论研究，推导得出采集得到的不同倾斜角的两幅光栅图像相位差与三维变形和形貌信息之间的关系，获取光栅的相位场并对该方法的精度进行了评估；下一步分析了薄膜测试系统中所需的光学显微系统存在的畸变误差，对显微镜成像畸变进行了标定，完成了聚酰亚胺薄膜、PET薄膜以及ITO薄膜/柔性基底力学性能的表征。原研究计划已顺利执行。