TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The catalyst is tris (dibenzylideneacetone-yl) dipalladium, tetrakis (triphenylphosphine) palladium or bis triphenylphosphine palladium dichloride, and is present in an amount of 0.05-20 mole%, preferably 10 mole%. The solvent is tetrahydrofuran, dimethyl ether, diethyl ether, benzene or toluene. Preferred Method: (IA) is prepared by dissolving 4-bromo-7-(7-bromo-5-iodo-2,1,3-benzoselenadiazol-4-yl)-6-iodo-2,1,3-benzoselenadiazole of formula (IC) and 2,5-dibromoselenopheno(3,2-b)selenophene compound of formula (ID) in solvent under the protection of inert gas atmosphere, then adding catalyst and alkali, stirring to react at 130 degrees C for 4 hours, separating lower layer and purifying. The mole ratio of alkali to (ID) is 1:1. The mole ratio of (IC) to (ID) is 1:2. (IC) is prepared by dissolving 2-amidogen-5 and pyridine in thionyl chloride to reflux at 80-90 degrees C for 24 hours, separating and purifying to obtain 5-nitro-2,1,3-benzothiadiazole, mixing 5-nitro-2,1,3 benzothiadiazole with hydrobromic acid to obtain a first mixture, heating the first mixture at 127 degrees C under reflux, dropwisely adding liquid bromine into the first mixture, refluxing for 4 hours, separating and purifying to obtain 4,7-dibromo-5-nitro-2,1,3 benzothiadiazole, adding diazosulfide with copper powder into 4,7-dibromo-5-nitro-2,1,3 benzothiadiazole, then adding N,N-dimethyl formamide, heating at 120 degrees C to react for 3 hours, separating and purifying to obtain 4,4'-dibromo-6,6'-dinitro-2,1,3 benzothiadiazole, adding 4,4'-dibromo-6,6'-dinitro-2,1,3 benzothiadiazole to tetrahydrofuran, then adding chloride solution, raising the temperature to 100 degrees C, heating and refluxing for 10 hours, separating and purifying to obtain 4,4'-dibromo-6,6'-diiodo-2,1,3-benzothiadiazole, adding ethanol in 4,4'-dibromo-6,6'-diiodo-2,1,3-benzothiadiazole to obtain suspension, then cooling the suspension to 0 degrees C, adding sodium borohydride to react at room temperature for 20 hours, separating and purifying to obtain 4,4'-dibromo-6,6'-diiodo-bis(1,2-phenylenediamine), mixing 4,4'-dibromo-6,6'-diiodo-bis(1,2-phenylenediamine) with ethanol to obtain second mixture, adding solution of selenium dioxide into the second mixture to reflux for 2 hours, filtering the reaction mixture. (IB) is prepared by dissolving compound of formula (IE) in solvent under the protection of the inert gas atmosphere, then adding n-butyl lithium into second mixture at 78 degrees C to react for 2 hours, then adding tributyltin chloride to react at 1-78 degrees C, reacting at room temperature for 6 hours, separating and purifying. The mole ratio of (IE) to n-butyl lithium is 1:2. The mole ratio of (IE) to tributyl tin chloride is 1:2. The Stille coupling reaction step comprises adding deionized water and toluene in the reaction liquid, decompressing and distilling the extracted organic phase concentrate, dropping anhydrous ethanol into the concentrate of the organic phase, continuously stirring, separating out solid precipitate, filtering, drying the solid powder, then dissolving solid powder in chloroform, removing chloroform using neutral aluminum oxide chromatographic column, depositing, filtering, then adding the obtained solid into a Soxhlet extractor for extracting, and then settling, filtering and purifying.