A layered perovskite structure comprising a substrate having an upper surface and a lower surface; and a layer of a perovskite film on the upper surface. A passivating layer may be applied to the upper surface of the substrate to which the perovskite film is attached. The passivating layer comprises at least one a chalcogenide-containing species with the general chemical formula (E3E4)N(E1E2)N′C═X where any one of E1, E2, E3 and E4 is independently selected from C1-C15 organic substituents comprising from 0 to 15 heteroatoms or hydrogen, and X is S, Se or Te, thiourea, thioacetamide, selenoacetamide, selenourea, H2S, H2Se, H2Te, or LXH wherein L is a Cn organic substituent comprising heteroatoms and X═S, Se, or Te. The substrate comprises PEDOT:PSS, and may further comprise a layered glass/ITO/PEDOT:PSS structure. A passivating layer is applied to the PEDOT:PSS layer, and a top electrode may be applied over the perovskite film.