TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The method further involves depositing the ink on a substrate to form precursor layer for growing copper (In, Ga) (VIA)2 compound film absorber of solar cell. The temperature during the formulation is 15degreesC or less. The precursor layer is heated to more than 15degreesC to form fused precursor layer. The formed layer is reacted with group (VIA) material such as selenium and sulfur to form group (IB,IIIA,VIA) compound film, at 350-600 degrees C. A transparent layer is deposited on the compound film to fabricate a solar cell. Copper-rich particles and solid Ga-In particles are placed in carrier liquid having temperature of 15degreesC or less to form a mixture. A dispersion forming agent is added to the mixture and agitated to form a dispersion. The solid Ga-In particles placed in carrier liquid are obtained by forming Ga-In melt at predetermined melting point, adding the melt in a liquid heated to predetermined melting temperature, agitating the obtained mixture to form emulsion (65) comprising nanoparticles (61), lowering the temperature of the emulsion to less than 15 degrees C, solidifying the particles to form nanoparticles and removing the formed particles. The copper-rich particles and Ga-In particles are obtained from powder mixture comprising group IB-rich particles and group IIIA-rich particles. Preferred Composition: The copper-rich particles comprise copper particles, copper-indium solid solution particles, copper-indium alloy particles, copper-gallium solid solution particles and copper-gallium alloy particles. The largest dimension of copper-rich particles and solid gallium-indium particles is less than 200 nm. The ink further comprises gallium particles or indium particles. The amount of copper-rich particles and solid gallium-indium particles placed in carrier liquid is selected to obtain predetermined copper/(indium+gallium) molar ratio, preferably 0.7-1 and predetermined gallium/(indium+gallium) molar ratio, preferably 0.2-0.8. The carrier liquid is water.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The method further involves depositing the ink on a substrate to form precursor layer for growing copper (In, Ga) (VIA)2 compound film absorber of solar cell. The temperature during the formulation is 15degreesC or less. The precursor layer is heated to more than 15degreesC to form fused precursor layer. The formed layer is reacted with group (VIA) material such as selenium and sulfur to form group (IB,IIIA,VIA) compound film, at 350-600 degrees C. A transparent layer is deposited on the compound film to fabricate a solar cell. Copper-rich particles and solid Ga-In particles are placed in carrier liquid having temperature of 15degreesC or less to form a mixture. A dispersion forming agent is added to the mixture and agitated to form a dispersion. The solid Ga-In particles placed in carrier liquid are obtained by forming Ga-In melt at predetermined melting point, adding the melt in a liquid heated to predetermined melting temperature, agitating the obtained mixture to form emulsion (65) comprising nanoparticles (61), lowering the temperature of the emulsion to less than 15 degrees C, solidifying the particles to form nanoparticles and removing the formed particles. The copper-rich particles and Ga-In particles are obtained from powder mixture comprising group IB-rich particles and group IIIA-rich particles. Preferred Composition: The copper-rich particles comprise copper particles, copper-indium solid solution particles, copper-indium alloy particles, copper-gallium solid solution particles and copper-gallium alloy particles. The largest dimension of copper-rich particles and solid gallium-indium particles is less than 200 nm. The ink further comprises gallium particles or indium particles. The amount of copper-rich particles and solid gallium-indium particles placed in carrier liquid is selected to obtain predetermined copper/(indium+gallium) molar ratio, preferably 0.7-1 and predetermined gallium/(indium+gallium) molar ratio, preferably 0.2-0.8. The carrier liquid is water.