A method for fabricating a doped conjugated polymer film includes the steps of: mixing a polar substance, a polar solvent and a doped conjugated polymer to form a doped conjugated polymer solution, and forming a conjugated polymer film with the doped conjugated polymer solution. In addition, a method for treating a doped conjugated polymer film includes the steps of: providing a doped conjugated polymer film, and adding a mixed solution which contains a polar substance and a polar solvent to the doped conjugated polymer film. In these cases, the polar substance is selected from the group consisting of formula (1), formula (2), inorganic acids, benzene-containing organic acids, or their combinations. The polar solvent is selected from the group consisting of water, ethers, alcohols, sulfoxides, alcohol ethers, ketones, amines, nitriles, carboxylic acids, amides, or their combinations.