Impact of various dopant elements on the electronic structure of Cu2ZnSnS4 (CZTS) thin films: a DFT study

Abstract

New structures made based on Cu₂ZnSnS₄ (CZTS) by substitutions with Cr, Ti, V, and Mo species were investigated via density functional theory. The total substitution of Zn by Cr and V leads to the vanishing of the bandgap, while n-type conductivity with a low bandgap of 0.19 eV was predicted in the case Ti. In addition, the conduction band minimum and valence band maximum overlapping were observed for the Mo/Sn ratio of 1/3. Therefore, our study suggests that even the low content of alternative cations in CZTS allows to control its band alignment. The obtained results can be helpful for designing CZTS-based intermediate layers to improve the quality of the back interface of the CZTS thin-film solar cells.