Selenium and Sulphur replacement dynamics in CZTSSe and CZGSSe kesterite materials

The replacement dynamics of Se by S is investigated in kesterite Cu 2 ZnSn(S,Se) 4 and Cu 2 ZnGe(S,Se) 4 . Two different post-sulphurization techniques yield the same results. In the initial stages of the replacement, the original selenium-rich phase coexists with a second mixed phase. This phase has an increased sulphur content of 30 %. In later stages of the reaction, the initial phase disappears in favor of the second phase. Thus, sulphur inclusions of less than 30% seem impossible while above 30% the sulphur amount is adjustable.