NOVELTY - An organic solar cell using a weak epitaxial film as a donor, comprises a transparent electrode made of indium tin oxide conductive glass; a conductive coating layer; a polycrystalline organic semiconductor induction layer having a thickness of not less than 2- not greater than 12 nm; a donor material layer having a thickness of not greater than 50 nm; a blending layer of donor material and receptor material and having a thickness of not greater than 60 nm; a receptor material layer having a thickness of not greater than 60 nm; an electrode buffer layer having a thickness of not less than 0.5- not greater than 10 nm; and a metal electrode made of silver or aluminum.    USE - An organic solar cell using a weak epitaxial film as a donor.    ADVANTAGE - The organic solar cell has improved performance and achieves an energy conversion efficiency of more than 3%.    DETAILED DESCRIPTION - An organic solar cell using a weak epitaxial film as a donor, comprises:    (1) a first layer which is a transparent electrode made of indium tin oxide conductive glass;    (2) a second layer which is a conductive coating layer of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate);    (3) a third layer which is a polycrystalline organic semiconductor induction layer having a thickness of not less than 2- not greater than 12 nm;    (4) a fourth layer which is a donor material layer having a thickness of not greater than 50 nm;    (5) a fifth layer which is a blending layer of donor material and receptor material and having a thickness of not greater than 60 nm;    (6) a sixth layer which is a receptor material layer having a thickness of not greater than 60 nm;    (7) a seventh layer which is an electrode buffer layer having a thickness of not less than 0.5- not greater than 10 nm; and    (8) an eighth layer which is a metal electrode made of silver or aluminum.    The polycrystalline organic semiconductor induction layer is made of 5,5'-bis(4-biphenylyl)-2,2'-bithiophene. The donor material is at least one of phthalocyanine containing no metal, phthalocyanine containing metal, pentacene, rubrene, thiophene oligomers, bithiophene oligomers and their functionalized variants. The receptor material is at least one of carbon allotrope, 3,4,9,10-perylenetetracarboxylic dianhydride, and their functionalized variants. The number of carbon atoms in the carbon allotrope is greater than 59 and less than 100. The electrode buffer layer is made of one of tris(8-hydroxyquinolinato)aluminum, bathocuproin and lithium fluoride. An average value of a root mean square (RMS) of a surface roughness of the transparent electrode is less than 1.5 nm. The thicknesses of the fourth and the fifth layers could not be zero at the same time. The thicknesses of the fifth and sixth layers could not be zero at the same time.