Recently, a world-record efficiency of 22.6% was achieved by applying a RbF postdeposition treatment (PDT) on a Cu(In,Ga)Se₂ (CIGSe) thin-film solar cell absorber surface. Here, we study the impact of this RbF-PDT on the electronic structure of the CIGSe surface and the CdS/CIGSe interface using ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS), as well as inverse photoemission spectroscopy (IPES). After RbF-PDT, we find a small downward shift of the band edges, while the surface band gap value itself is not affected. In addition, a further downward band bending in the CIGSe absorber is observed upon formation of the RbF-PDT CdS/CIGSe interface. We derive a flat conduction band alignment between the RbF-PDT CIGSe absorber and the CdS buffer, commensurate with the high efficiencies of solar cell devices prepared with RbF-PDT.

中文翻译：

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RbF后沉积处理对高效薄膜太阳能电池中CdS / Cu（In，Ga）Se ₂异质结电子结构的影响

最近，通过在Cu（In，Ga）Se ₂上进行RbF沉积后处理（PDT），实现了创纪录的22.6％的效率。（CIGSe）薄膜太阳能电池吸收器表面。在这里，我们使用紫外和X射线光电子能谱（UPS和XPS）以及反光电子能谱（IPES）研究了RbF-PDT对CIGSe表面和CdS / CIGSe界面电子结构的影响。在RbF-PDT之后，我们发现带边缘有一个小的向下偏移，而表面带隙值本身不受影响。另外，在形成RbF-PDT CdS / CIGSe界面时，在CIGSe吸收器中观察到了进一步的向下带弯曲。我们推导了RbF-PDT CIGSe吸收体和CdS缓冲液之间的平坦导带对准，这与用RbF-PDT制备的太阳能电池器件的高效率相称。