TECHNOLOGY FOCUS - IMAGING AND COMMUNICATION - Preferred Method: The metal chalcogen nanoparticle dispersion is deposited onto the substrate using spin-coating, dip-coating, doctor blading, curtain coating, slide coating, spraying, slit casting, meniscus coating, screen printing, ink jet printing, pad printing, flexographic printing or gravure printing.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The method-I further comprises washing the metal chalcogenide nanoparticles with water containing at least one of a source of sulfur and a source of selenium. The method-II further comprises adjusting the pH of the ink to greater than 7 using an inorganic additive. The content of the zinc chalcogenide distributed within the surface layer of the metal chalcogenide nanoparticles is sufficient to inhibit agglomeration of the metal chalcogenide nanoparticles in water at a pH of 7-14 without the use of organic additives or ligands. The zinc chalcogenide distribution within the surface layer of the metal chalcogenide nanoparticles is achieved by an additional step of contacting the metal chalcogenide nanoparticles with an additional source of zinc and optionally an additional source of chalcogen. The nanoparticles are separated from the dissolved product using filtration or centrifugation. The conditions further comprises a temperature of 20-50 degrees C. The layer is heated to a temperature of 300-700 degrees C for a duration of 1-120 minutes to form the kesterite film. The layer is heated in an atmosphere containing vapors of at least one of sulfur, selenium and tin. Preferred Components: The metal chalcogenide nanoparticles are a homogeneous or heterogeneous mixture comprising at least one of amorphous and crystalline compounds. The source of zinc comprises elemental zinc, zinc oxide, zinc hydroxide, zinc bromide, zinc fluoride, zinc iodide, zinc chloride, zinc sulfate or zinc nitrate. The source of copper comprises elemental copper, copper oxide, copper hydroxide, copper bromide, copper fluoride, copper iodide, copper chloride, copper sulfate or copper nitrate. The source of tin comprises elemental tin, tin oxide, tin hydroxide, tin bromide, tin fluoride, tin iodide, tin chloride, tin sulfate or tin nitrate. The source of sulfur comprises ammonium sulfide, alkali metal sulfide or hydrogen sulfide. The source of selenium comprises ammonium selenide, alkali metal selenide or hydrogen selenide. The additional source of zinc comprises zinc (Zn2+) ions. The solvent comprises water and a water-hydrazine mixture. The inorganic additive is ammonium compound. The substrate comprises one or more of a metal foil substrate, aluminum foil coated with a layer of molybdenum, a glass substrate with conductive coating, a ceramic substrate with conductive coating and a polymer substrate with conductive coating. The ink has a pH of 9-14. EXAMPLE - Zinc chloride (0.067 g), copper chloride (0.967 g) and tin chloride (0.765 g) were dissolved in water (30 ml) (full dissolution can be achieved by addition of hydrochloric acid). Then, ammonium selenide solution (5 ml) was added to the mixture with stirring, and then a solution of zinc chloride (0.600 g) in water (10 ml) and ammonium sulfide solution (5 ml) were added. The solution was sonicated for 10 minutes, stirred again and separated by two consecutive cycles of centrifugation and washing with 2-3% of aqueous ammonium sulfide. The final wet cake was dispersed with the addition of water to form metal chalcogenide nanoparticles (12 ml).