NOVELTY - Manufacturing a solar cell comprises sequentially preparing a substrate (1), an anode (2), a hole transport layer (3), an active layer (4) and a cathode (5), where the hole transport layer is poly(3,4-ethylenedioxythiophene) or poly(sodium styrene sulfonate); and preparing the electron transport layer (6) between the active layer and the cathode. The electron transport layer is a carboxylic containing compound.    USE - Method for manufacturing a solar cell.    ADVANTAGE - The method is simple, has low production cost, and can provide solar cell having high open-circuit voltage and which provides good performance of the device.    DETAILED DESCRIPTION - Manufacturing a solar cell comprises sequentially preparing a substrate (1), an anode (2), a hole transport layer (3), an active layer (4) and a cathode (5), where the hole transport layer is poly(3,4-ethylenedioxythiophene):poly(sodium styrene sulfonate); and preparing the electron transport layer (6) between the active layer and the cathode. The electron transport layer is a carboxylic containing compound of formula (A), where the degree of polymerization of the polymer can be 1-300. The polymer is manufactured by obtaining a nitrogen dioxide containing compound of formula (B) through decarboxylation nitration of the compound (A), reducing into an amine compound of formula (C), then diazotizing, and reacting with potassium ethyl xanthate to produce a sulfobenzene containing compound (D); diazotizing aromatic amine containing compound of formula (E), and reacting with sodium iodide to synthesize an aromatic iodo-product of formula (F); and reducing the compound (D) into thiophenol of formula (G), and dissolving with aromatic chloride of formula (H) or the aromatic iodo-product (F) under the effect of a basic catalyst to obtain the compound (I).    DESCRIPTION OF DRAWING(S) - The drawing is a schematic diagram of the solar cell.    Substrate (1)    Anode (2)    Hole transport layer (3)    Active layer (4)    Cathode (5)    Electron transport layer (6)