Effect of Combined Alkali (KF plus CsF) Post-Deposition Treatment on Cu(InGa)Se2 Solar Cells

This study reveals combined alkali (KF+CsF) post-deposition treatment (PDT) effects on a Cu(InGa)Se-2 (CIGSe) cell. Three different alkali-PDTs (KF, CsF, and combined KF+CsF) on CIGSe thin films have been performed. The CIGSe cell with KF-PDT exhibits further reduction in the recombination at the CdS/buffer interface, whereas the CIGSe cell with CsF-PDT exhibits further reduction in the recombination in bulk. In addition, the CIGSe cell with combined alkali-PDT exhibits reduced recombination at both the CdS/CIGSe interface and in bulk compared to all other cells. By applying the combined alkali-PDT, a highly efficient CIGSe device with 20.15% is achieved.