NOVELTY - Making (P1) a thin film solar cell on a substrate involves: (a) providing a substrate coated with an electrical contact layer; (b) depositing a first layer of a first ink onto the contact layer of the substrate, where the first ink contains a first polymeric precursor compound that is enriched in the quantity of a Group 11 atom; (c) heating the first layer; (d) depositing a second layer of a second ink onto the first layer, where the second ink contains at least one indium/aluminum/gallium compound; and (e) heating the layers.    USE - For making thin film solar cell on substrate, where the substrate is 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, gallium, gold, lead, manganese, molybdenum, nickel, palladium, platinum, rhenium, rhodium, silver, stainless steel, steel, iron, strontium, tin, titanium, tungsten, zinc, zirconium, metal alloy, a metal silicide, a metal carbide, a polymer, plastic, conductive polymer, a copolymer, polymer blend, polyethylene terephthalate, polycarbonate, polyester, polyester film, a mylar, polyvinyl fluoride, polyvinylidene fluoride, polyethylene, polyetherimide, polyethersulfone, polyetherketone, polyimide, polyvinylchloride, an acrylonitrile butadiene styrene polymer, silicone, an epoxy, paper, and/or coated paper (claimed).    ADVANTAGE - The method provides solar cells having high efficiencies for conversion of light; and provides predetermined stoichiometry for solar cells.    DETAILED DESCRIPTION - Making (P1) a thin film solar cell on a substrate involves: (a) providing a substrate coated with an electrical contact layer; (b) depositing a first layer of a first ink onto the contact layer of the substrate, where the first ink contains a first polymeric precursor compound that is enriched in the quantity of a Group 11 atom; (c) heating the first layer; (d) depositing a second layer of a second ink onto the first layer, where the second ink contains at least one compound having formula M'b(E'R')3; and (e) heating the layers.    M'b=In, Ga, or Al;    E'=S or Se;    R'=alkyl, aryl, heteroaryl, alkenyl, amido, silyl, or inorganic and organic groups.    INDEPENDENT CLAIMS are included for the followings:    (1) a solar cell made by the process (P1);    (2) an ink composition for making a solar cell, comprising In(SeR)3 or Ga(SeR)3.    R=alkyl or aryl.