NOVELTY - Preparation of a thin film solar cell on a substrate involves: providing a substrate (10) coated with an electrical contact layer (20); depositing a bottom layer (30) of a first ink containing polymeric precursor compounds onto the contact layer of the substrate; heating the bottom layer; depositing a top layer (40) of a second ink containing metal atom chalcogenide inorganic source compounds onto the bottom layer; and heating the top and bottom layers.    USE - For the preparation of a thin film solar cell on a substrate selected from a semiconductor, a doped semiconductor, silicon, gallium arsenide, insulators, glass, molybdenum glass, silicon dioxide, titanium dioxide, zinc oxide, silicon nitride, a metal, a metal foil, molybdenum, aluminum, beryllium, cadmium, cerium, chromium, cobalt, copper, gold, manganese, molybdenum, nickel, palladium, platinum, rhenium, rhodium, silver, stainless steel, steel, iron, strontium, tin, titanium, tungsten, zinc, zirconium, a metal alloy, a metal silicide, a metal carbide, a polymer, a plastic, a conductive polymer, a copolymer, a polymer blend, a polyethylene terephthalate, a polycarbonate, a polyester, a polyester film, a mylar, a polyvinyl fluoride, polyvinylidene fluoride, a polyethylene, a polyetherimide, a polyethersulfone, a polyetherketone, a polyimide, a polyvinylchloride, an acrylonitrile butadiene styrene polymer, a silicone, an epoxy, paper, and/or coated paper (claimed).    ADVANTAGE - The method is used to control stoichiometry of metal atoms in making a solar cell for targeting a particular concentration and providing a gradient of metal atom concentration. The polymeric precursor compounds are stable in inert atmosphere and advantageously allow control of the stoichiometry, structure, and ratios of the atoms in a semiconductor material or layer, in particular, metal atoms and atoms of Group 11. Using polymeric precursor compounds in any particular semiconductor manufacturing process, the stoichiometry of monovalent metal atoms and Group 11 atoms can be determined and controlled. As compared to processes involving several sources for semiconductor preparation, the present method by using polymeric precursors provide enhanced control of the uniformity, stoichiometry and properties of a semiconductor material. The polymeric precursors are superior building blocks for semiconductor materials because they provide atomic-level control of semiconductor structure; and allow direct and precise control of the stoichiometric ratios of metal atoms. Using the method chemically and physically uniform semiconductor layers can be prepared with polymeric precursor compounds; and solar cells and other products can advantageously be made in processes operating at relatively low temperatures using the polymeric precursor compounds and compositions. The polymeric precursor compounds provide enhanced processability for solar cell production; and have an ability to be processed at relatively low temperatures, as well as the ability to use a variety of substrates including flexible polymers in solar cells.    DETAILED DESCRIPTION - Preparation of a thin film solar cell on a substrate involves: providing a substrate (10) coated with an electrical contact layer (20); depositing a bottom layer (30) of a first ink containing polymeric precursor compounds onto the contact layer of the substrate; heating the bottom layer; depositing a top layer (40) of a second ink containing metal atom chalcogenide inorganic source compounds onto the bottom layer; and heating the top and bottom layers. The first ink is enriched or deficient in the quantity of a Group 11 atom. Each heating process is a process involving converting the layer at 100-400 (preferably 170-350) degrees C, and annealing the layer at 450-650 (preferably 450-575) degrees C. The method further involves depositing an ink containing In(S(S)Bu)3 after the last heating step; depositing a chalcogen ink layer or chalcogen vapor onto the top layer; and applying heat, light, or radiation, or adding at least one chemical or crosslinking reagent to the second ink before depositing the second ink onto the substrate, or to the first ink before depositing the first ink onto the substrate. An INDEPENDENT CLAIM is included for a solar cell made by the process.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a solar cell.    Substrate (10)    Electrode layer (20)    Absorber layer (30)    Buffer layer (40)    Transparent conductive layer (50)