Karas Joseph, Phua Benjamin, Mo Alvin, Iqbal Nafis, Davis Kristopher, Bowden Stuart, Lennon Alison, Augusto André
Solar Power Laboratory, Arizona State University, Tempe, Arizona 85287, United States.
School of Photovoltaic and Renewable Energy Engineering, University of New South Wales, Sydney, New South Wales 2052, Australia.
ACS Appl Mater Interfaces. 2022 Mar 16;14(10):12149-12155. doi: 10.1021/acsami.1c21218. Epub 2022 Mar 3.
Plated copper (Cu) contacts for silicon (Si) solar cells are an attractive alternative material to conventional screenprinted silver, but there are unresolved questions on the long-term integrity of plated contact structures. In this work, we perform characterization on plated Cu contacts from encapsulated cells that were degraded during extended exposure to damp heat (DH) stress. First, using energy-dispersive X-ray spectroscopy, we find evidence of Cu outdiffusion upward through capping layers made of both tin and silver applied with light-induced plating, resulting in a layer of Cu on the outer contact surface. We hypothesize that if Cu is mobile in the module, it may eventually find some route by which to enter the Si cells where it can degrade performance. Subsequently, in several types of Cu-plated, DH-degraded cells, secondary ion mass spectrometry detects elevated levels of Cu at the Si surface and in the Si cell bulk, which suggests that Cu can indeed migrate from contacts into Si over the course of DH stress.
用于硅（Si）太阳能电池的电镀铜（Cu）触点是传统丝网印刷银的一种有吸引力的替代材料，但电镀触点结构的长期完整性存在尚未解决的问题。在这项工作中，我们对在长时间暴露于湿热（DH）应力下退化的封装电池的电镀铜触点进行了表征。首先，使用能量色散X射线光谱法，我们发现有证据表明铜通过光诱导电镀施加的锡和银制成的覆盖层向上向外扩散，导致外部接触表面形成一层铜。我们推测，如果铜在组件中具有流动性，它最终可能会找到某种途径进入硅电池，从而降低其性能。随后，在几种类型的电镀铜、经DH退化的电池中，二次离子质谱法检测到硅表面和硅电池本体中的铜含量升高，这表明在DH应力过程中，铜确实可以从触点迁移到硅中。
