The invention discloses a method for manufacturing an electron transfer layer in a solar cell. The polymer is a monomer polymer with a structural formula (I), wherein n is any integer between 1 and 300. The method comprises the following steps of: performing decarboxylative nitration on a compound 1 to obtain a compound 2 under the action of concentrated nitric acid and acetic acid, reducing the compound 2 into a compound 3 by using zinc powder/acetic acid or palladium on carbon/hydrazine hydrate, preparing a diazonium salt solution by using sodium nitrite and hydrochloric acid, and reacting with potassium ethyl xanthogenate to generate a compound 4; (2) preparing aromatic amine 5 into a diazonium salt solution by using sodium nitrite and hydrochloric acid, and reacting with sodium iodide to synthesize an aromatic iodo product 6; (3) dissolving the compound 4 in tetrahydrofuran, and reducing the compound 4 into thiophenol 7 by using lithium aluminum hydride; and (4) dissolving the aromatic iodo product 6 and the thiophenol 7 in ethylene glycol and isopropanol or toluene and other solvents, and synthesizing the material with the general formula I under the action of potassium carbonate and cuprous iodide. The solar cell manufactured by taking the material as the electron transfer layer has high open-circuit voltage, so that the solar cell has good device performance.