NOVELTY - A complex film counter electrode has sequential arrangement of conductive substrate, carbon material film and polythiophene film which are connected through intermolecular forces and interatomic action force. The polythiophene film is polythiophene film or polythiophene derivative film.    USE - Complex film counter electrode is used for dye-sensitized solar cell.    ADVANTAGE - The complex film counter electrode having excellent electrochemical stability and catalytic performance is economically prepared. The dye-sensitized solar cell comprising the complex film counter electrode has high photoelectric conversion efficiency.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of complex film counter electrode. Carbon material is reacted with mixed acid at constant temperature of 50-70 degrees C for 5-7 hours, filtered, washed using distilled water and dried at 50-70 degrees C for 10-15 hours under vacuum at 50-70, to obtain surface-modified carbon material. The surface-modified carbon material is dispersed into aprotic organic solvent for 20-40 minutes and ultrasonically agitated, to obtain electrophoresis solution of carbon material. The mixed acid is mixture of concentrated sulfuric acid with concentration of 98 weight% and concentrated nitric acid with concentration of 69 weight% in volume ratio of 3:1. The ratio of the weight (g) of the carbon material to the volume (mL) of mixed acid is 1:60-100. The ratio of the weight (mg) of the surface modified carbon material with respect to volume of mixed acid is 1:1. Carbon material film is deposited on the substrate using electrophoresis solution of carbon material with conducting substrate as anode and platinum electrode as cathode under a direct current voltage of 40-60 V through 10-20 minutes of electrophoresis. The distance between the cathode and the anode is 0.5-1 cm. The conductive substrate with the carbon material film is dried at 70-90 degrees C under vacuum, to form carbon material film on the conductive substrate. The thiophene or thiophene derivative monomer is dissolved in boron trifluorene diethyl etherate, to obtain thiophene or thiophene derivative electrolytic deposition solution. The concentration of the thiophene or thiophene derivative is 15-20 mmol/L. Cyclic voltammetry scanning within a scanning range of -0.8-1.6 V of thiophene or thiophene derivative electrolytic deposition solution is carried out at scanning speed of 0.05 V/second in electrochemical workstation with triode-electrode system in which the conductive substrate with the carbon material film serves as working electrode, platinum electrode as the counter electrode and a saturated calomel electrode or a silver/silver chloride electrode as reference electrode. The initial level is set to -0.8 V. Then, the working electrode is washed using de-ionized water and dried at 70-90 degrees C under vacuum for 10-15 hours, to obtain the carbon material/polythiophene complex film counter.