Recent progress in nanostructured siler sulfide: from synthesis and nonstoichiometry to properties

The microstructure (composition, nonstoichiometry, size and shape of particles) of nanostructured semiconductor silver sulfide (Ag2S) determines its electronic structure, optical and electrical properties, and possible applications of Ag2S in modern electronics, biology and medicine. This critical review summarizes recent progress in the design of different forms of nanostructured Ag2S from nanopowders to colloidal solutions, quantum dots and heteronanostructures. Main results on the synthesis, structural features and properties of nanostructured Ag2S are detailed. The appearance of nonstoichiometry in silver sublattices of monoclinic Ag2S at decreasing size particles to the nanometer scale is considered. The interdependent changes in nonstoichiometry and crystal structure at the transformation of a nonconducting nanocrystalline Ag2S in superionic conductors are discussed. The effects of nanocrystalline state on the peculiarities of crystal structure, nonstoichiometry, optical and thermal properties of semiconductor Ag2S are considered. Special attention is paid to manifold applications of Ag2S-based nanomaterials and heteronanostructures in biomarkers, resistance-switches and nonvolatile memory devices.