NOVELTY - An organic active-layer (14) solution for a polymer solar cell (10) comprises an organic active-layer material; a first organic solvent (s1), having a boiling point of 50-200 degrees C; and a second organic solvent (s2), having a boiling point of 150-300 degrees C.    USE - As organic active-layer solution for a polymer solar cell (claimed).    ADVANTAGE - The organic active-layer simplifies manufacturing process of a polymer solar cell and increases power conversion efficiency of the polymer solar cell. The second organic solvent has high boiling point (lower volatility), therefore it does not volatilize easily; and it lowers an evaporation speed of the organic active-layer solution during a solvent annealing process, without requiring an environment having a high saturated vapor pressure or a closed environment. Therefore, the time needed to complete the solvent annealing process can be reduced, and a manufacturing process of the polymer solar cell is simplified. At the same time, a power conversion efficiency of the polymer solar cell can also be increased. The addition of the second organic solvent directly lowers the volatility and evaporation speed of the organic active-layer solution, so that the organic polymer molecules in the organic active-layer solution are arranged in a more orderly manner. Therefore, when the method for preparing the organic active-layer solution is used in mass production, the power conversion efficiency of the polymer solar cell thus made can be increased while the manufacturing process of the polymer solar cell is simplified, where no additional special environments, such as an environment having a high saturated vapor pressure or a closed environment, are required. Using the method, no special environmental condition is required, thus lowering production cost of the polymer solar cell.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparing an organic active-layer solution involving providing an organic active-layer material; dissolving the organic active-layer material in first organic solvent (s1); and adding second organic solvent (s2) into the first organic solvent.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic structural drawing of the polymer solar cell.    Polymer solar cell (10)    Substrate (11)    Conductive layer (12)    Conductive polymer layer (13)    Organic active layer (14)    Electrode (15)