TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparation of fluorene copolymer containing thiophene-quinoxaline compound (I) involves subjecting dibromo quinoxaline compound of formula (X), cyclopenta diene compound of formula (XI), substituted cyclopenta diene compound of formula (XII) in coupling reaction to obtain thiophene quinoxaline compound of formula (XIII) in the presence of catalyst and organic solvent. Thiophene quinoxaline compound of formula (XIII) and N-bromosuccinimide are subjected to substitution reaction of bromine the presence of organic solvent to obtain bis dibromo quinoxaline compound of formula (XIV). Boron substituted diphenyl compound of formula (IX), substituted dibromo compound of formula (Br-Ar1-Br) and bis dibromo quinoxaline compound of formula (XIV) are subjected to coupling reaction in the presence of organic solvent under oxygen-free alkali condition to obtain the fluorene copolymer containing thiophene quinoxaline. Preferred Components: The catalyst utilized in coupling reaction is organic palladium catalyst and/or organic phosphine ligand. The alkyl derivative of lithium is chosen from n-butyl lithium, t-butyl lithium, methyl lithium and phenyl lithium. The organic solvent utilized in coupling reaction is chosen from methylbenzene, tetrahydrofuran, diethyl ether and ethyl acetate. The organic solvent utilized in substitution reaction is chosen from N-dimethylform amide, tetrahydrofuran, diethyl ether, dichloromethane, trichloromethane, ethyl acetate and acetic acid. The organic solvent is chosen from tetrahydrofuran, diethyl ether, dichloromethane, trichloromethane or ethyl acetate. Preferred Composition: The mol ratio of dibromo quinoxaline compound (X), cyclopenta diene compound (XI), substituted cyclopenta diene compound (XII) is 2.0:a:b, where a is more than b, b is more than 0 and a+b is 2-4. The amount of dibromo quinoxaline compound (X) is 0.05-20%. The mol ratio of thiophene quinoxaline compound (XIII) to N- bromo succinimide is 1:2.0-2.5. The mol ratio of boron substituted diphenyl compound (IX), substituted dibromo compound to thiophene quinoxaline compound (XIII) is 1.0: c: d, where c is more than 0, d is more than 0, and c+d is 1. The mol ratio of 2,7- dibromo-9,9- dialkyl fluorene, alkyl derivative of lithium to 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-oxa pentaborane is 1:2.0-4.0: 2.0-4.0. The mol ratio of Ar1 compound to N-bromo succinimide in substituted dibromo compound preparation method is 1: 2.0-2.5. Preferred Process: The preparation method of boron substituted diphenyl compound (IX) involves reacting 2, 7- dibromo-9,9-dialkyl fluorene, alkyl derivative of lithium and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-oxa pentaborane in the presence of organic solvent under anhydrous, oxygen-free environment to obtain the product. The reaction temperature of the coupling reaction is 60-120 degrees C for 12-24 hours. The reaction temperature of dibromo product in substitution reaction is 0-30 degrees C for 12-48hours. The reaction temperature in boron substituted diphenyl compound (IX) preparation method is -100 to -25 degrees C. The preparation method of substituted dibromo compound involves reacting unbrominated Ar1 compound with N-bromo succinimide to obtain the product. The reaction temperature in the substituted dibromo compound preparation method is 0-30 degrees C.