Abstract In this paper, we propose a possible explanation of the limited CuIn1-xGaxSe2 (CIGSe) performance at high Ga contents, related to the properties of detrimental copper selenide (CuδSe) secondary phases. We study CIGSe layers at different x, by means of X-ray diffraction analyses, Raman and energy dispersive X-ray spectroscopy. Our results reveal that for high Ga contents, CuδSe secondary phases either precipitate at the interfaces between grains or remain within the layer as intra- or inter-grain clusters, deteriorating the electronic properties of the absorber layer. On the contrary, for low Ga contents, the copper selenide segregates at the surface of the CIGSe and hence it can be easily removed by KCN surface etching. To understand the CuδSe precipitation within the bulk of the film for a high Ga ratio, we also investigate In-free CGSe samples at low and high Cu content. Our observations demonstrate that i) CuδSe has a preferential grain orientation to segregate and ii) the Cu-enriched regions within the bulk of the high Ga content films are more a kinetic than a thermodynamic issue.

中文翻译：

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CuIn1-xGaxSe2 薄膜太阳能电池中有害的硒化铜块状沉淀。大 x 性能有限的可能原因？

摘要 在本文中，我们提出了在高 Ga 含量下有限的 CuIn1-xGaxSe2 (CIGSe) 性能的可能解释，这与有害的硒化铜 (CuδSe) 二次相的性质有关。我们通过 X 射线衍射分析、拉曼和能量色散 X 射线光谱研究不同 x 的 CIGSe 层。我们的结果表明，对于高 Ga 含量，CuδSe 第二相要么在晶粒之间的界面处沉淀，要么作为晶粒内或晶粒间簇留在层内，从而降低吸收层的电子特性。相反，对于低 Ga 含量，硒化铜在 CIGSe 表面偏析，因此可以通过 KCN 表面蚀刻轻松去除。为了了解高 Ga 比率下薄膜主体内的 CuδSe 沉淀，我们还研究了低和高 Cu 含量的无 In CGSe 样品。我们的观察表明 i) CuδSe 具有优先晶粒取向以进行偏析和 ii) 高 Ga 含量薄膜主体内的富铜区域更多是动力学问题而不是热力学问题。