TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Material: The precursor material (p1) further comprises a source of extra chalcogen material mixed with the core-shell nanoparticles. Preferred Components: In material (p1), the core nanoparticles include nanoparticles of a group IB element (preferably copper), and nanoparticles of at least one group IIIA element (preferably indium and/or gallium). In material (p1), the non-oxygen chalcogen material is selenium and/or sulfur and/or tellurium. In material (p1), the core-shell nanoparticles include core nanoparticles of a binary alloy or a ternary alloy. The binary alloy contains a group IB element (preferably copper) and a chalcogen (preferably selenium or sulfur or tellurium); or contains a group IIIA element (preferably indium or gallium) and/or a chalcogen (preferably selenium or sulfur or tellurium). The ternary alloy contains two different group IIIA elements (preferably indium and gallium) and a chalcogen (selenium and/or sulfur and/or tellurium). In material (p2), the source of extra chalcogen includes particles of an elemental chalcogen (preferably selenium and/or sulfur and/or tellurium). In material (p2), the element of group IIIA includes gallium and/or indium and/or aluminum. In material (p2), the group IB-chalcogenide nanoparticles includes nanoparticles of copper selenide and/or copper sulfide and/or copper telluride. In material (p2), the group IIIA-chalcogenide nanoparticles includes nanoparticles of indium selenide, and/or nanoparticles of indium sulfide, and/or nanoparticles of indium telluride, and/or nanoparticles of gallium selenide and/or nanoparticles of gallium sulfide and/or gallium telluride. In material (p2), the group IB-chalcogenide nanoparticles and/or the group IIIA-chalcogenide nanoparticles include a chalcogenide core with a chalcogen-containing coating, where the coating provides the extra source of chalcogen. In method (m1), the nanoparticle precursor material includes group IB-chalcogenide nanoparticles containing a chalcogenide material in the form of an alloy of a chalcogen and an element of group IB; and/or the nanoparticle precursor material includes group IIIA-chalcogenide nanoparticles containing a chalcogenide material in the form of an alloy of a chalcogen and at least one element of group IIIA. In method (m1), the group IB chalcogenide is a non-oxide chalcogenide; the group IIIA chalcogenide is a non-oxide chalcogenide; and the source of extra chalcogen includes particles of an elemental chalcogen, or is in the form of a powder containing sub-micron or micron-sized particles. In method (m1), the nanoparticles (preferably having a size of less than 500 nm, especially less than 200 nm) of chalcogenide materials include indium sulfide, and/or copper sulfide and/or gallium sulfide nanoparticles; or include indium telluride, and/or copper telluride and/or gallium telluride nanoparticles. In method (m1), the nanoparticle precursor further includes nanoparticles and/or nanoglobules and/or nanodroplets of metallic gallium. The core-shell nanoparticles include core nanoparticles of a binary alloy containing two group IIIA elements. Preferred Method: In method (m1), the nanoparticles include a chalcogenide core with a chalcogen-containing coating that provides the extra source of chalcogen; forming the nanoparticle precursor includes forming a dispersion containing the nanoparticles; and heating the nanoparticles includes heating the nanoparticle precursor to greater than 375degreesC but less than a maximum temperature (preferably less than 500degreesC, especially less than 575degreesC) for processing the substrate. In method (m1), disposing the nanoparticles on the substrate includes a non-vacuum technique, or includes a solution based coating technique. The solution based coating technique is chosen from web coating, spray coating, spin coating, doctor blade coating, printing techniques including contact printing, gravure printing, microgravure printing, ink-jet printing or jet deposition. The method (m1) further involves solidifying the dense film; and mixing the powder into a dispersion containing the group IB-chalcogenide nanoparticles and/or the group IIIA-chalcogenide nanoparticles. Disposing the group IB-chalcogenide nanoparticles and/or group IIIA-chalcogenide nanoparticles and a source of extra chalcogen on a surface of a substrate includes depositing the powder onto the substrate prior to, or after depositing a dispersion containing the group IB-chalcogenide nanoparticles and/or the group IIIA-chalcogenide nanoparticles. In method (m1), disposing the nanoparticles and extra source of chalcogen on the surface of the substrate includes forming a film of the dispersion on a substrate; mixing the source of extra chalcogen with the group IB-chalcogenide nanoparticles and/or group IIIA-chalcogenide nanoparticles; sequentially depositing at least two layers of nanoparticle precursor materials having different compositions of IB-, IIIA- and/or non-oxygen chalcogen-based particulates; or depositing a first layer containing a group IIIA non-oxygen chalcogenide nanopowder and subsequently depositing a second layer containing a group IB non-oxide chalcogenide nanopowder and/or a different group IIIA non-oxide chalcogenide nanopowder, and further depositing a layer containing a non-oxygen chalcogen. Heating the nanoparticle precursor material and source of extra non-oxygen chalcogen includes sintering the first and second layers together (preferably sintering the first layer before sintering the second layer). The method (m1) alternately involves obtaining core nanoparticles containing at least one element from group IB and/or IIIA; coating the core nanoparticles with an elemental non-oxygen chalcogen material to produce core-shell nanoparticles; disposing a film containing the core-shell nanoparticles on a surface of a substrate; heating the film to a temperature sufficient to melt the non-oxygen chalcogen material and to react the non-oxygen chalcogen material with the group IB and group IIIA elements to form a dense film of a group IB-IIIA-non-oxide chalcogenide compound; and further involves mixing a source of extra non-oxygen chalcogen material with the core-shell nanoparticles. The disposing the core-shell nanoparticles on the surface of the substrate includes forming ink containing the core-shell nanoparticles; or forming a film of the ink on a substrate. Disposing the film containing the core-shell nanoparticles on the surface of the substrate includes sequentially depositing at least two layers of nanoparticle precursors having different compositions of IB-, IIIA- and non-oxygen chalcogen-based particulates. Heating the film includes sintering at least two layers together; or sintering a first layer before sintering a second layer.    TECHNOLOGY FOCUS - METALLURGY - Preferred Components: The substrate is a flexible substrate; and is a metallic foil made of a metal chosen from aluminum, molybdenum, titanium, steel, and/or their alloys, and/or similar metals.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The substrate is a polymer substrate or a metallized polymer substrate.