TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): The compound (I) is prepared by dehydrating the dione compound and 3,4-diaminothiophene.hydrogen chloride to obtain 2,3-disubstituted-thieno(3,4-b)pyrazine; making the N-bromosuccinimide (NBS) and 2,3-disubstituted-thieno(3,4-b)pyrazine to perform bromination to obtain target monomer; and polymerizing the 4,4-dialkyl-2,6-bis(trimethylsilyl)-cyclopentadiene(2,1-6:3,4-b')bithiophene, 4,4-dialkyl-2,6-dibromo- cyclopentadiene(2,1-b:3,4-b')bithiophene and the target monomer in the organic solvent in absence of oxygen. Preferred Method: The first step comprises dehydrating the dione compound and 3,4-diaminothiophene.hydrogen chloride at a mole ratio of 1: 0.1-10 with absolute alcohol for 1-24 hours at 0-78 degrees C. The reaction solution in the dehydrating reaction comprises methanol, alcohol, ethyl acetate or water. A triethylamine or sodium carbonate catalyst is added in the dehydrating reaction, in which the mole ratio of the amount of the triethylamine or sodium carbonate and the 3,4-diaminothiophene.hydrogen chloride is 1: 2-50. The sodium carbonate is added in reaction system after having been prepared into the solution and the concentration of the solution is 0.1-2mol/L. The mole ratio of NBS and 2,3-disubstituted-thieno(3,4-b)pyrazine in the second step is 1: 10-10. The temperature of bromination is 0-70 degrees C and the reaction time is 1-48 hours. The reaction solution of the bromination is mixed solution of chloroform and acetic acid, tetrahydrofuran or N,N-dimethylformamide, in which the volume ratio of chloroform and acetic acid in the mixed solution is 1: 0.1-10. The third step comprises polymerizing the 4,4-dialkyl-2,6-bis(trimethylsilyl)-cyclopentadiene(2,1-6:3,4-b')bithiophene, 4,4-dialkyl-2,6-dibromo-cyclopentadiene(2,1-b:3,4-b')bithiophene and 5,7-dibromo 2,3-bisubsistuted-thieno(3,4-b)pyrazine in the organic solution for 24-72 degrees C at mole ratio of m: p: q at 40-110 degrees C, in which m is p+q and p is more than m and not less than 0. Catalyst is added in the polymerizing reaction and the mole ratio of catalyst and 4,4-dialkyl-2,6-dibromo- cyclopentadiene(2,1-b:3,4-b')bithiophene is 0.05-50%. The catalyst is the mixture of organic palladium catalyst or organic palladium catalyst and organic phosphorus, in which the organic palladium catalyst is tris(dibenzylideneacetone)dipalladium(0), (triphenylphosphine)palladium, or (triphenylphosphine)palladium and the mole ratio of the organic palladium catalyst and the organic palladium catalyst is 1: 2-20. The organic solution in the third step is tetrahydrofuran, dimethoxyethane, benzene or methylbenzene. The first and third steps are performed in anaerobic environment. Inert gas is filled in anaerobic environment.