TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The dye-sensitized solar cell has working electrode, counter electrode, and electrolyte provided between working electrode and counter electrode.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The oxidizing agent is oxygen gas, chlorine and/or bromine gas, tris(4-bromophenyl)aminium hexachloroantimonate, organic acid chosen from propionic acid, trifluoroacetic acid, toluenesulfonic acid and dodecylbenzenesulfonic acid, and inorganic acid chosen from iron(III) chloride hexahydrate, anhydrous iron chloride(III), iron(III) nitrate nonahydrate, anhydrous ferric nitrate, and iron (III) perchlorate. The content of gas in oxidizing agent with respect to 1 L of electrolyte solution is 1-50 mg/L. The total content of inorganic acid and organic acid in oxidizing agent with respect to 100 %mass of electrolyte solution is 0.001-10 %mass. The working electrode contains dye adsorbed on the electrode layer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Process: The chemical oxidation involves immersing the electroconductive polymer in the solution obtained by dissolving oxidizing agent. The electrochemical oxidation involves immersing working electrode (11) in electroconductive polymer solution-containing supporting electrolyte, and applying predetermined voltage to working electrode. Preferred Composition: The electroconductive polymer is a polymer of thiophene compound of formula (I), pyrrole compound of formula (II), and aniline compound of formula (III). The dye-sensitized solar cell comprises electrolyte solution containing 1 or more oxidizing agents which can oxidize electroconductive polymer by chemical oxidation. The gross mass ratio of photoacid generator to the gross mass of electroconductive polymer is 0.01-10.R1-R8=H, 1-8C alkyl, 1-4C alkoxy, 6C or 8C aryl, carboxy, ester, aldehyde, halo, OH, CN, amino, nitro, or sulfo.(i) When R1 and R2 are alkyl or aryl, the alkyl or aryl bonds to thiophene ring through azo or sulfonyl group; (ii) When R1 and R2 are alkyl or alkoxy, the alkyl or alkoxy bond together to form ring; (iii) When R3 and R4 are alkyl or aryl, the alkyl or aryl bonds to pyrrole ring through azo or sulfonyl group; (iv) When R3 and R4 are alkyl or alkoxy, the alkyl or alkoxy bonds together to form ring; (v) When R5 and R6, or R7 and R8 are alkyl or aryl, the alkyl or aryl bonds with benzene through azo or sulfonyl group; and (vi) When R5 and R6, or R7 and R8 are alkyl or alkoxy, the alkyl or alkoxy bonds together to form a ring.