Depth profiling of degradation of multilayer photovoltaic backsheets after accelerated laboratory weathering: Cross-sectional Raman imaging
Depth profiling of degradation of multilayer photovoltaic backsheets after accelerated laboratory weathering: Cross-sectional Raman imaging
复制标题
DOI：
10.1016/j.solmat.2015.09.021
复制
发表时间：
2016-01-01
影响因子：
6.9
通讯作者：
Gu, Xiaohong
中科院分区：
文献类型：
--
作者：
Lin, Chiao-Chi;Krommenhoek, Peter J.;Gu, Xiaohong
了解多层光伏（PV）背板中每一层及其界面的耐用性对于设计和选择材料以制造可靠和高性能的光伏模块至关重要。在本研究中，利用拉曼成像技术，在NIST（美国国家标准与技术研究所）SPHERE（模拟高能辐射光降解）上，对暴露于85摄氏度、5%相对湿度（干燥）和85摄氏度、60%相对湿度（潮湿）的紫外线（UV）辐射下的多层商业背板薄膜的化学降解进行了深度分析。背片膜是由着色的聚对苯二甲酸乙二醇酯（PET）基外层、PET核心层和三层乙酸乙烯乙烯（EVA）组成的多层层压板，以及PET外层和PET核心层之间的两层内粘接层，以及PET核心层和EVA层。通过冷冻显微切开术制备横断面样品以进行各种表征。利用激光扫描共聚焦显微镜和原子力显微镜对多层结构进行了表征，并利用拉曼光谱成像获得了多层结构的化学降解谱。老化后的背板膜降解不均匀，紫外线和水分对多层膜的降解曲线有显著影响。高荧光显示，在着色PET外层的最外层区域发生了严重的降解，降解梯度延伸到主体约20 μ m。还发现，在潮湿条件下，内层粘合层严重恶化，这表明在潮湿环境中使用多层背板时，层之间的长期粘合可能是一个主要关注的领域。讨论了尖锐的（不均匀的）退化轮廓、由此产生的内应力和最终破坏（开裂和分层）之间的关系。Elsevier B.V.出版
Understanding of the durability of each individual layer and their interfaces in a multilayered photovoltaic (PV) backsheet is critical to the design and selection of materials for making reliable and high performance PV modules. In this study, Raman imaging was used to depth profile the chemical degradation of a multilayer commercial backsheet film exposed to ultra-violet (UV) radiation at 85 degrees C, 5% relative humidity (RH, dry) and 85 degrees C, 60% RH (humid) on the NIST (National Institute of Standards and Technology) SPHERE (Simulated Photo-degradation via High Energy Radiant Exposure). The backsheet film was a multipart laminate comprising of a pigmented polyethylene terephthalate (PET)-based outer layer, PET core layer and three ethylene vinyl acetate (EVA) layers having different vinyl acetate (VA) contents, along with two inner adhesive layers between PET outer and PET core layers, and PET core and EVA layers. Cross-sectional samples were prepared by cryo-microtomy for various characterizations. The multilayer structures were examined by laser scanning confocal and atomic force microscopies, while their chemical degradation profiles were obtained by Raman spectroscopic imaging. Non-uniform degradation was observed in the aged backsheet film, and both UV and moisture appeared to significantly affect the degradation profiles of the multilayers. Severe degradation, indicated by high fluorescence, occurred in the outermost region of the pigmented PET outer layer, and the degradation gradient extended to approximately 20 mu m to the bulk. It was also found that the inner adhesive layers were severely deteriorated under moist condition, indicating that the long-term adhesion between the layers could be a major area of concern for multilayer backsheets used in a humid environment. The relationship between the sharp (non-uniform) degradation profile, resultant internal stress, and ultimate failures (cracking and delamination) was discussed as well. Published by Elsevier B.V.