“…Semiconductor metal sulfides, especially MoS 2 , , Bi 2 S 3 , CuS, CdS, ZnS, and PbS and A 2 S 3 -M 2 S 3 -M‘S (A = Ga, In; M = trivalent metal; M‘ = divalent metal), , have attracted ever increasing attention in the past few years, due to their excellent physical as well as chemical properties. But very recently, a considerable amount of interest has been focused on copper sulfides owing to their variations in stoichiometric composition, valence states, nanocrystal morphologies, complex structures, and different unique properties. , The stoichiometric composition of copper sulfide varies in a wide range from Cu 2 S at the copper-rich side to CuS 2 at the copper-deficient side, such as CuS, Cu 1.96 S, Cu 1.94 S, Cu 1.8 S, Cu 7 S 4 , and Cu 2 S …”