Formation of a KInSe Surface Species by NaF/KF Postdeposition Treatment of Cu(In,Ga)Se₂ Thin-Film Solar Cell Absorbers

A NaF/KF postdeposition treatment (PDT) has recently been employed to achieve new record efficiencies of Cu­(In,Ga)­Se₂ (CIGSe) thin film solar cells. We have used a combination of depth-dependent soft and hard X-ray photoelectron spectroscopy as well as soft X-ray absorption and emission spectroscopy to gain detailed insight into the chemical structure of the CIGSe surface and how it is changed by different PDTs. Alkali-free CIGSe, NaF-PDT CIGSe, and NaF/KF-PDT CIGSe absorbers grown by low-temperature coevaporation have been interrogated. We find that the alkali-free and NaF-PDT CIGSe surfaces both display the well-known Cu-poor CIGSe chemical surface structure. The NaF/KF-PDT, however, leads to the formation of bilayer structure in which a KInSe species covers the CIGSe compound that in composition is identical to the chalcopyrite structure of the alkali-free and NaF-PDT absorber

Additional file 1: of The antibiotic resistome and microbiota landscape of refugees from Syria, Iraq and Afghanistan in Germany

Supplemental Material and Methods. (DOCX 1405 kb