Enhancement of charge collection at shorter wavelengths from alternative CdS deposition conditions for high efficiency CZTSSe solar cells

A cadmium sulfide (CdS) layer with a thickness of 37±5 nm is deposited onto a Cu2ZnSn(SSe)4 absorber layer using Cd(NO3)2 precursor at pH 11.8 via chemical bath deposition. Full devices fabricated with the thin CdS layer show improved champion efficiency of 6.97%, compared with the 5.91% efficiency of the control device, which can be attributed to the increased current density from reduced light reflection in the visible region and enhanced charge collection in the shorter wavelength region.