柔性太阳能电池器件的结构优化和疲劳分析

The base plus island design of substrate has shown much improved stretchability of photovoltaic devices. However, this structured substrate is selective in the island height in isolating deformations, and bending deformation is inevitably produced to the solar cell due to Poisson's effect when the substrate is stretched. What is more, it is in a dilemma in choosing the thickness of the flat encapsulation layer, which needs to increase thickness to suppress the solar cell deformation but to lower thickness to reduce the interface shear stress. These design limitations have the device's stretchability degraded, and the existence of interface shear stress has strong negative effects on its fatigue life. Therefore, it is proposed in this project a superb structured substrate, which includes base, island and the columns interconnecting them. At the same time the encapsulation layer will also be structured and the adhesion area will also be reduced. The design with maximized deformation isolation effect for the device as a whole will be explored through simulations, theory models and experimental testings. Furthermore, a theory model accounting for fatigue damage will be established for interface strength and the fatigue life of new design device will be investigated by finite element method and experiments. All these research activities and the achievements, will fully improve the device's stretchability and thus enhance its fatigue life substantially. This research project does not only have science significance, but also definitely boost the practical implementations of flexible photovoltaics devices.

基底加岛体的结构化设计使得柔性太阳能电池器件具有良好的延展性。然而该设计在变形隔离上有特殊的岛体高度选择性，而且基体变形通过泊松效应对电池模块产生弯曲变形。保护膜的平板设计使得其厚度必须在抑制电池模块的弯曲变形（增加厚度）和降低界面剪应力（减小厚度）之间作出两难选择。这些设计中的不足不仅限制柔性太阳能电池器件的延展性，界面剪应力的存在也对电池器件的使用寿命产生负面影响。因此，本项目提出基底、岛体和连接二者柱体的优化基体结构化，并对保护膜进行结构化设计，减小粘接面积，结合数值模拟、理论分析和实验测试来实现具有最佳变形隔离效应的整体设计方案。同时建立界面强度的疲劳损伤理论模型，通过有限元计算和实验测试来研究电池器件的疲劳性能。本项目的研究成果将充分增加柔性太阳能器件的延展性，显著提高其疲劳寿命。该研究不仅具有重要的科学意义，而且有助于加速促进柔性太阳能电池器件的实际研发和应用。

该课题以柔性电子太阳能电池的弹性基底为研究对象，主要探讨在保持器件整体功能性的前提下基底的优化设计，以提高器件的延展性和柔韧性。为此，我们分别从模拟和实验开展相关研究工作。通过有限元模拟计算与分析，我们发现在所提出的衬底-立柱-岛体的基底优化设计中，中间立柱的宽度对变形隔离效应有非常重要的影响，立柱-岛体整体的高度对变形隔离效应有影响。此外，对于界面的损伤累积与破坏理论模型已经建立，数值模拟工作还在进行当中。在实验方面，我们已经成功制备出这种三层复合结构基底，目前正在研发基于这种优化基底的电子设备，如柔性LED显示器、柔性传感器等。