TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation comprises taking substituted 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9H-fluorene compound of formula (II), substituted 1,3-dibromo-4H-thieno(3,4-c)pyrrole-4,6(5H)-dione compound of formula (III), substituted thiophene compound of formula (IV), substituted tributyl(thiophen-2-yl)stannane compound of formula (V) and 5,7-dibromo-2,3-dihydrothieno(3,4-b)(1,4)dioxine; performing coupling reaction of compounds (III), (IV) and (V) in presence of a catalyst and an organic solvent to obtain substituted 1,3-di(thiophen-2-yl)-4H-thieno(3,4-c)pyrrole-4,6(5H)-dione compound of formula (VI); performing bromination of (VI) and aging to obtain a dibromo product; and performing Suzuki reaction of (II), (VI) and the dibromo-product in presence of a catalyst, alkali solution and organic solvent. Preferred Method: The coupling reaction comprises reacting (III), (IV) and (V) in presence of a catalyst and an organic solvent for 12-24 hours at 60-120 degrees C according to a molar ratio of 2:a:b to obtain a coupling product, where the catalyst is organic palladium or a mixture of organic palladium and organic phosphorus ligand, the quantity of the catalyst is 0.005-0.1 times the molar quantity of (III), and the organic solvent is a weakly polar and/or a polar aprotic organic solvent. The bromination comprises adding a coupling agent and a brominating agent into an organic solvent at 0-30 degrees C in a molar ratio of 1:2-2.5, and reacting for 12-48 hours to obtain dibromo-product, where the organic solvent is a weakly polar and/or a polar aprotic organic solvent. The Suzuki reaction comprises taking (II), (VI) and dibromo-product in a molar ratio of 1:c:d, reacting (II), (VI) and dibromo-product in presence of a catalyst, alkali solution and organic solvent in oxygen-free environment for 24-72 hours at 65-120 degrees C to obtain (I), where the catalyst is organic palladium or a mixture of organic palladium and organic phosphorus ligand, the quantity of the catalyst is 0.005-0.1 times the molar quantity of (III), the alkali solution is aqueous solution of alkali metal hydroxide or alkali metal carbonate or tetraalkylammonium hydroxide, the quantity of the alkali in the alkali solution is 2-20 times of molar quantity of (II), and the organic solvent is a weakly polar and/or polar aprotic organic solvent. The preparation of (II) comprises mixing 2,7-dibromo-9,9-dialkylfluorene and alkyl lithium in an organic solvent at -100 to -25 degrees C according to a molar ratio of 1:2-1:4, adding 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, and reacting for 24-48 hours to obtain (II), where the organic solvent is a weakly polar and/or polar aprotic organic solvent, and the quantity of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane is 2-4 times the molar quantity of 2,7-dibromo-9,9-dialkylfluorene. The preparation of (III) comprises: (i) adding thiophene-3,4-dicarboxylic acid into acetic anhydride, stirring for 12-24 hours, vacuum extracting and evaporating the solvent in the reaction liquid, adding into an organic solvent, adding an alkylamine, heating to 100-120 degrees C for 24-32 hours, cooling, vacuum extracting and removing the solvent, adding thionyl chloride, heating to 80-100 degrees C and refluxing for 1-12 hours to obtain 5-alkyl thiophene(3,4-c)-pyrrole-4,6-dione, where the alkyl in alkylamine is R3; and (ii) adding 5-alkyl thiophene(3,4-c)-pyrrole-dione and a brominating agent into an organic solvent at 10-30 degrees C in a molar ratio of 1:2-1:4, and reacting for 12-48 hours.either a, b = greater than 0; ora+b = 0-4; andeither c, d = greater than 0; orc+d = 0.9-1.1. Preferred Definitions:    R1-R7 = 8-20C alkyl; and    n = 20-80.