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 C2h2-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).