Effect of native point defects on the photocatalytic performance of ZnIn2S4

Understanding of materials at atomic scale is mandatory for improving their physical properties in the desired way. Here, first-principles calculations with the most accurate hybrid functional are performed to investigate one of the most attractive photocatalyst ZnIn2S4. The electronic structures of perfect and defective cubic-ZnIn2S4 are examined as a representative of other ZnIn2S4 polymorphs. The influence of growth conditions on the photocatalytic activity of ZnIn2S4 is elucidated by considering the formation energy of native point defects under different growth conditions. Our results reveal that undoped ZnIn2S4 is a native n-type material owning to the high pinned Fermi-level under all growth conditions. The source of electron carriers in undoped ZnIn2S4 is the InZn antisite defect and its photocatalytic performance is declined by the formation of dominant compensating Zn vacancy defect. The S-poor growth condition of undoped ZnIn2S4 is unveiled to provide the best photocatalytic performance due to the highest pinned Fermi-level.