NOVELTY - Preparation of stable n-doped conjugated electroactive polymer having pyrazole-containing repeating unit (I) involves contacting platinum substrate with a solution containing monomeric thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole (a) in tetramethylammonium tetrafluoroborate, selecting electrical potentials (A) and (B) to oxidize and reduce pyrazole (a), respectively, applying preset electrical potential to platinum substrate, and growing a film of stable n-doped poly(thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole) on platinum substrate.    USE - Preparation of stable n-doped conjugated electroactive polymer used for forming batteries and supercapacitors.    ADVANTAGE - The method enables simple and stable preparation of stable n-doped conjugated electroactive polymer.    DETAILED DESCRIPTION - Preparation of stable n-doped conjugated electroactive polymer having pyrazole-containing repeating unit of formula (I) involves providing a solution containing monomeric thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole in tetramethylammonium tetrafluoroborate and acetonitrile, contacting a platinum substrate with the solution, selecting electrical potential (A) to oxidize thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole and electrical potential (B) to reduce thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole, applying an electrical potential to the platinum substrate in contact with solution, repeating the electrical potential at a predetermined rate of change between electrical potentials (A) and (B) in cycles to effect electrodeposition of poly(thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole) on platinum substrate, and growing a film of stable n-doped poly(thiophene substituted 3,5-dithien-2-yl-4,4-disubstituted pyrazole) of preset thickness on the platinum substrate by repeating the electrical potential in cycles for predetermined time.    R1-R3=H, 1-22C alkyl, 1-22C alkoxy, nitro, halo, cyano ester, 1-22C mono- or di-alkylamino, 1-22C ester groups, 1-22C amido, 1-22C alcohol, amino, sulfonato, silyl, 1-22C perfluoro alkyl;and    n=2-200.