Electronic, optical, and mechanical properties of Cu₂ZnSnS₄ with four crystal structures

The structural, electronic, optical, and mechanical properties of Cu₂ZnSnS₄ with four crystal structures are calculated using the density functional theory. No significant difference is observed between the calculated optical and mechanical properties of the considered four crystal structures. The calculated results are in agreement with available reported experimental data. According to the calculated results, the fundamental band gap of Cu₂ZnSnS₄ is mainly determined by the bandwidth of the isolated conduction band. The effective-mass of carriers of Cu₂ZnSnS₄ are very small, especially the effective-mass of electrons on the bottom of the conduction band of zincblende-derived Cu₂ZnSnS₄. Using the calculated elastic constants matrix, the Born stability criteria is shown to be satisfied, and the high B/G ratio indicates that Cu₂ZnSnS₄ is prone to ductile behavior. (paper)