NOVELTY - The method comprises preparing a substrate having a back electrode layer (3) formed on one surface of the substrate, preparing a first mixture containing copper, selenium, indium and optional gallium at a smaller composition ratio as compared to indium and the second mixture containing copper, selenium, gallium and optional indium at a smaller composition ratio as compared to gallium in a liquid medium, applying a layer of one of the mixtures onto the back electrode layer, drying the applied layer of the mixture, and rapidly baking the dried layer of the mixture.    USE - The method is useful for forming a light absorber layer of a chalcopyrite thin film solar cell, which is useful for mass producing solar cells.    ADVANTAGE - The method is capable of simply forming the light absorber layer thus efficiently and economically manufacturing the solar cells having a large surface area with improved performance and high conversion efficiency.    DETAILED DESCRIPTION - The method comprises preparing a substrate having a back electrode layer (3) formed on one surface of the substrate, preparing a first mixture containing copper, selenium, indium and optional gallium at a smaller composition ratio as compared to indium and the second mixture containing copper, selenium, gallium and optional indium at a smaller composition ratio as compared to gallium in a liquid medium, applying a layer of one of the mixtures onto the back electrode layer, drying the applied layer of the mixture, rapidly baking the dried layer of the mixture by radiating infrared and laser energy, repeating the applying, drying and baking steps until all of the mixtures are applied to the back electrode layer, and applying a transparent electrode layer on an outer surface of the lastly applied sub-layer of mixture. The liquid medium comprises an organic solvent. The mixtures are prepared by mixing small particles of members consisting of gallium, indium, gallium compound and indium compound in the liquid medium, where the small particles consist of nano particles.    DESCRIPTION OF DRAWING(S) - The diagram shows a copper indium gallium selenide absorber layer.    Soda-lime glass substrate (2)    Back electrode layer (3)    Light absorber layer (4)    Inks. (10)