NOVELTY - The method involves forming (s10) an electrode in a substrate. A mixed thin film layer is formed (s12) by mixing an electron donor material with a sacrificial polymer i.e. polyalkylene glycol. A nano-structured electron donor material is formed (s14) by removing the sacrificial polymer in the mixed thin film layer during heat treatment process. An electron acceptor material layer is formed (s16) on the nano-structured electron donor material. Another electrode is formed (s18) on the electron acceptor material layer.    USE - Method for fabricating a solar cell that is utilized in a semiconductor device.    ADVANTAGE - The method enables providing nanostructure material with a photoactive layer so as to increase optical absorption efficiency and separation efficiency of electron and hole, thus improving photoelectric conversion efficiency of a solar cell. The method enables simplifying solar cell manufacturing process, so that manufacturing cost of the solar cell can be reduced. The method enables increasing crystallization of electron donor material so as to increase moving efficiency of electric charge.    DETAILED DESCRIPTION - The polyalkylene glycol is polyethylene glycol or polypropylene glycol. The electron donor material is pentacene, coumarin, zinc phthalocyanine, phthalocyanine, titanium oxide phthalocyanine, copper hexadecafluorophthalocyanine, subphthalocyanine chloride, poly (3-hexylthiophene-2, 5-diyl), platinum, poly (3-octylthiophene-2, 5-diyl), poly(2, 1, 3-benzothiadiazole-4, 7-diyl(4, 4-bis(2-ethylhexyl)-4H-cyclopenta(2, 1-b:3, 4-b')dithiophene-2, 6-diyl)), poly((9-(1-octylnonyl)-9H-carbazole-2, 7-diyl)-2, 5-thiophenediyl-2, 1, 3-benzothiadiazole-4, 7-diyl-2, 5-thiophenediyl), poly((9-(1-octylnonyl)-9H-carbazole-2, 7-diyl)-2, 5-thiophenediyl-2, 1, 3-benzothiadiazole-4, 7-diyl-2, 5-thiophenediyl), poly(2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene), poly(2-methoxy-5-(3', 7'-dimethyloctyloxy)-1, 4-phenylenevinylene), perfluorooctanoic acid and poly(9, 9-dioctylfluorenyl-2, 7-diyl). The electron acceptor layer is an n-type organic semiconductor layer or an n-type metal oxide layer. The n-type organic semiconductor layer is butyric acid methyl ester, N, N'-bis(2, 5-di-tert-butylphenyl)-3, 4, 9, 10-perylene-tetracarboxylic acid diimide, perylene-3, 4, 9, 10-tetracarboxylic acid N, N'-dipenthylimide, perylene-3, 4, 9, 10-tetracarboxylic bis-benzimidazde, antra(2", 1", 9":4, 5, 6, 6", 5", 10":4', 5', 6')diisoquino(2, 1-a:2', 1'-a')diperimidine-12, 25-dione, perylene-3, 4, 9, 10-tetracarboxylic dianhydride, perylene-3, 4, 9, 10-tetracarboxylic acid dimide, (1, 4, 5, 8-naphthalenetetracarboxylic dianhydride), perylene-3, 4, 9, 10-tetracarboxylic acid N, N'-dimethylimide, perylene-3, 4, 9, 10-tetracarboxylic acid N, N'-diheptylimide, 8-hydroxyquinolinolato-lithium, 2, 2', 2"-(1, 3, 5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole), (2, 9-dimethyl-4, 7-diphenyl-1. 10-phenanthroline), (2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline), (4, 7-diphenyl-1, 10-phenanthroline), (bis(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminum), (1, 3-bis(2-(2, 2'-bipyridine-6-yl)-1, 3, 4-oxa)    DESCRIPTION OF DRAWING(S) - The drawing shows a flow diagram illustrating a method for fabricating a solar cell.'(Drawing includes non-English language text)'    Electrode forming step (s10, s18)    Mixed thin film layer forming step (s12)    Nano-structured electron donor material forming step (s14)    Electron acceptor material layer forming step (s16)