TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The catalyst in Suzuki coupling reaction is organic palladium or mixture of organic palladium and organophosphorus ligand in the mol ratio of 1:2-20. The mol amount of the catalyst in Suzuki coupling reaction is 0.05-20% of that of compound (3). The organic solvent is the weak polar and/or polar aprotic organic solvent.    TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Fluorene aldehyde compounds (1,2) and 2-(1H-pyrrol-2-ylmethyl)-1H-pyrrole are subjected to polycondensation oxidation in a system containing catalyst, oxidizing agent and organic solvent to obtain 5,15-bis(9,9-dialkyl fluorene)porphyrin. The obtained compound is brominated to obtain 5,15-dibromo-10,20-bis(9,9-dialkyl fluorene)porphyrin. The dibromo compound and spiro compound of formula (3) are subjected to Suzuki coupling reaction in the presence of catalyst and organic solvent to obtain the porphyrin copolymer. Preferred Component: Each unit of porphyrin copolymer containing thienothiadiazole units has the same two alkyl-containing fluorene groups. Preferred Process: The polycondensation oxidation reaction is performed in the absence of water and oxygen. The compounds (1,2) are dissolved in organic solvent and organic acid is added as catalyst. The contents are stirred for 1-24 hours at 20-100 degrees C and 2,3-dichloro-5,6-dicyanobenzoquinone is added as oxidizing agent, and stirred for 1-60 minutes. Triethylamine is added to quench the reaction to obtain the copolymer. The Suzuki coupling reaction involves adding compound (3) and 5,15-dibromo-10, 20-bis(9,9-dialkyl fluorene)porphyrin into organic solvent in the mol ratio 1:1.5-1.5:1 and vacuumized to remove oxygen and filled with protective gas. The catalyst is added and heated to 50-120 degrees C and reacted for 12-80 hours. The reaction liquid is added in aqueous solution of sodium diethyldithiocarbamate after being cooled, and the mixed liquid is heated to 60-80 degrees C and stirred for 12-14 hours.