Synthesis and crystal and defect structures of polycrystalline Cu2SrSnS4 and Cu1.9SrSnS4 powders

The polycrystalline samples of Cu2 – _δSrSnS4 with a trigonal structure were prepared by solid-phase ampoule synthesis with a long annealing time (1944 h), and their crystal lattice parameters were refined and Raman spectra were obtained. For the first time, the effect of defect structure on the lifetimes of photogenerated current carriers in the polycrystalline powders was examined by combining time-resolved microwave photoconductivity and cathodoluminescence methods. A significant increase in the lifetimes during the conversion of Cu₂SrSnS₄ into Cu_1.9SrSnS₄ was found, which was probably due to changes in the defect structure.