Abstract Thin film Cu(In,Ga)Se2 (CIGS) solar modules can be grown on flexible and lightweight substrates allowing their direct integration into building elements. Such multifunctional building elements would significantly reduce the installation cost of photovoltaic systems provided that CIGS solar cells with high conversion efficiency can be obtained. Also, there is a need for low cost substrate foil. Mild steel is a promising low cost substrate material due to its excellent mechanical stability and already wide acceptance as component in building envelopes and in numerous other applications. During the growth of the CIGS absorber layer certain elements, e.g. iron, can diffuse from the metallic substrate into the semiconductor deteriorating the device performance. Here we present an effective diffusion barrier and device architecture for processing of highly efficient CIGS solar cells on mild steel substrates. The CIGS absorber layers were grown on mild steel foils by a multistage co-evaporation process at different substrate temperatures. The mild steel substrates were plated with an industrially scalable electrodeposited Ni/Cr bi-layer. The diffusion barrier layer properties of this Ni/Cr coating were investigated directly by measuring the metallic impurities within the absorber by secondary ion mass spectrometry and indirectly by admittance spectroscopy. The Ni/Cr bi-layer was found to be effective up to a nominal CIGS growth temperature of 500 °C. A certified cell efficiency of 18.0% was achieved on a Ni/Cr coated mild steel substrate using a low temperature CIGS deposition process and a NaF and RbF post deposition treatment method.

中文翻译：

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低成本低碳钢基板上的 Cu(In,Ga)Se 2 太阳能电池

摘要 薄膜 Cu(In,Ga)Se2 (CIGS) 太阳能模块可以在柔性轻质基板上生长，从而使其直接集成到建筑元素中。如果可以获得具有高转换效率的CIGS太阳能电池，这种多功能建筑元件将显着降低光伏系统的安装成本。此外，需要低成本的基材箔。低碳钢是一种很有前途的低成本基材，因为它具有出色的机械稳定性，并且已被广泛用作建筑围护结构和许多其他应用中的组件。在 CIGS 吸收层的生长过程中，某些元素（例如铁）会从金属衬底扩散到半导体中，从而降低器件性能。在这里，我们提出了一种有效的扩散屏障和器件架构，用于在低碳钢基板上加工高效 CIGS 太阳能电池。CIGS 吸收层通过多级共蒸发工艺在不同的基板温度下生长在低碳钢箔上。低碳钢基材镀有工业规模的电沉积镍/铬双层。通过二次离子质谱法和导纳光谱法间接测量吸收体中的金属杂质，直接研究了这种 Ni/Cr 涂层的扩散阻挡层特性。发现 Ni/Cr 双层在高达 500 °C 的标称 CIGS 生长温度下是有效的。经认证的电池效率为 18。