Enhanced Photoelectric SrOCuSbS₂ of a [SrO]-Intercalated CuSbS₂ Structure

A new two-dimensional (2D) layered oxysulfide, namely, SrOCuSbS₂, was successfully synthesized at 160 °C by using a hydrazine-hydrothermal method. The compound crystallizes in the space group C_{2 h}²- P2₁/ m (No. 11) of the monoclinic system. The crystal structure is composed of distorted chalcostibite-like _∞²[CuSbS₂O]^2- layers along the ab plane, in which the adjacent layers are separated by Sr²⁺ ions. Each layer contains infinite _∞¹[Cu₂S₆]^10- chains linked by [SbS₄O]^7- units. The optical band gap of the compound is 1.9 eV, presenting the dark red color. Due to the electronic insulating layer (EIL) of the SrO, SrOCuSbS₂ shows a high photoelectric property with a photocurrent density of 3.5 mA/cm² at 1 V. The results of density of states (DOS) reveal that the valence band maximum (VBM) mainly consists of Cu-3d and S-3p states, while Sb-5p, S-3p, and S-3s contribute to the conductive band minimum (CBM).