TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The alkali solution is aqueous sodium carbonate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The catalyst is tris(dibenzylideneacetone)dipalladium (0), bis(triphenylphosphine)palladium(II) dichloride and tetrakis(triphenylphosphine)palladium(0). The organic solvent (s1) is toluene and N,N-dimethylformamide. Preferred Process: The separation and purification of alkylene-containing fluorene-thieno(3,4-b)pyrazine polymer is carried out by adding toluene and deionized water to the reaction system, extracting, performing vacuum distillation of organic phase, adding anhydrous methanol, stirring, precipitating, filtering, drying obtained solid powder, dissolving solid powder in chloroform, removing catalyst using alumina column, performing liquid chromatography, concentrating by rotary evaporation, dripping methanol, stirring in a solvent, drying, obtaining crude product and extracting crude product in Soxhlet extractor. The fluorene derivative (II) is prepared by adding fluorene compound of formula (IV) to an anhydrous reactor under the protection of nitrogen, adding organic solvent (s2), slowly adding n-butyllithium at -70 degrees C to -85 degrees C, stirring, reacting, slowly adding 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-di(hetero)borane oxopentyl, heating at room temperature for 10-48 hours, separating and purifying. The fluorene compound (IV) is prepared by dissolving 9-(bis(methylsulfanyl)methyl)-2,7-dibromo-9H-fluorene in organic solvent (s3) at -5 degrees C to -10 degrees C in nitrogen atmosphere with constant stirring, adding ether solution containing alkyl magnesium bromide of formula: R1MgBr (V), reacting at -20 degrees C to 0 degrees C for 35-40 minutes, adding dilithium tetrachlorocuprate dissolved in tetrahydrofuran, stirring, adding sodium hydroxide solution, reacting for 10-20 minutes, separating and purifying. 9-(Bis(methylsulfanyl)methyl)-2,7-dibromo-9H-fluorene is prepared by dissolving 2,7-dibromo-fluorene in anhydrous dimethyl sulfoxide at room temperature under nitrogen atmosphere, adding potassium tert-butoxide, uniformly stirring, adding carbon disulfide, reacting, adding iodomethane, stirring for 4-6 hours, separating and purifying.    TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): The alkylene-containing fluorene-thieno(3,4-b)pyrazine polymer is prepared by dissolving fluorene derivative of formula (II), 5,7-dibromo-5H,7H-thieno(3,4-b)pyrazine compound of formula (III) and catalyst in organic solvent (s1) in molar ratio of 1:1:0.005-0.05, adding an alkali solution at 60-100 degrees C under reflux for 24-72 hours, separating and purifying.