Formation of a K-In-Se Surface Species by NaF/KF Postdeposition Treatment of Cu(In,Ga)Se2 Thin-film Solar Cell Absorbers
ACS Applied Materials and Interfaces
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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. © 2017 American Chemical Society.
Wilks, R. G.,
Kreikemeyer Lorenzo, D.,
Tiwari, A. N.,
Formation of a K-In-Se Surface Species by NaF/KF Postdeposition Treatment of Cu(In,Ga)Se2 Thin-film Solar Cell Absorbers.
ACS Applied Materials and Interfaces, 9(4),