TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The molar ratio of compound (A) to compound (B) is 1:1.5-1.5:1. The ratio of 4-nitrobenzene-1,2-diamine and thionyl chloride is 1.5:1 mol/l. The volume ratio of thionyl chloride and pyridine is 50:1. The content of hydrobromic acid is 40 %mass. The volume ratio of 5-nitro-2,1,3-benzothiadiazole and hydrobromic acid is 4:1 mol/L. The volume ratio of 5-nitro-2,1,3-benzothiadiazole and liquid bromine is 5.3:1 mol/L. The molar ratio of 4,7-dibromo-5-nitro-2,1,3-benzothiadiazole and copper powder is 0.2:1. The molar ratio of 4,4'-dibromo-6,6'-dinitro-linked-2,1,3 benzothiadiazole and stannous chloride is 1:10. The molar ratio of 4,4'-dibromo-6,6'-dinitro-linked-2,1,3-benzothiadiazole and hydrochloric acid is 0.92:1. The molar ratio of 4,4'-dibromo-6,6'-dinitro-linked-2,1,3-benzothiadiazole and sodium nitrite is 0.53:1. The molar ratio of 4,4'-dibromo-6,6'-dinitro-linked-2,1,3 benzothiadiazole and potassium iodide is 0.054:1. The molar ratio of 4,4'-dibromo-6,6'-diiodo-linked-2,1,3 benzothiadiazole and dichlorosilane compound (C) is 2:1. The catalyst is tris (dibenzylideneacetone)dipalladium, bis (triphenylphosphine) palladium dichloride, or tetrakis(triphenylphosphine) palladium. The addition amount of catalyst is 0.5-20 mol%. The organic solvent is tetrahydrofuran, ethylene glycol dimethyl ether, benzene, or toluene.    TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Bromo derivative of dibenzothiadiazole compound (A) of formula (II) and tributyl tin derivative (B) of formula (III) are dissolved in organic solvent in inert gas atmosphere, catalyst is added, and Stille coupling reaction is carried out at 50-120 degrees C for 6-100 hours, to obtain dibenzothiadiazole copolymer (I). Preferred Process: 4-Nitrobenzene-1,2-diamine with thionyl chloride and pyridine are reacted at 80-90 degrees C for 24 hours, and 5-nitro-2,1,3-benzothiadiazole is separated. 5-Nitro-2,1,3-benzothiadiazole and liquid bromine or hydrobromic acid are subjected to bromination reaction at 127 degrees C for 4 hours, to obtain 4,7-dibromo-5-nitro-2,1,3-benzothiadiazole. 4,7-Dibromo-5-nitro-2,1,3-benzothiadiazole is subjected to catalytic coupling reaction at 120 degrees C for 3 hours, in presence of copper powder catalyst to obtain 4,4'-dibromo-6,6'-dinitro-linked-2,1,3 benzothiadiazole. 4,4'-Dibromo-6,6'-dinitro-linked-2,1,3 benzothiadiazole is subjected to reduction reaction using stannous chloride at 100 degrees C for 10 hours such that nitro group is reduced to amino group, and diazotization reaction is carried out with sodium nitrite in presence of hydrochloric acid and then reacted with potassium iodide, to obtain 4,4'-dibromo-6,6'-diiodo-linked-2,1,3-benzothiadiazole. 4,4'-Dibromo-6,6'-diiodo-linked-2,1,3-benzothiadiazole is reacted with n-butyl lithium and dichlorosilane compound (C) of formula: R1-Si(-R2)(-Cl)-Cl (IV) in presence of dimethylformamide solvent under anaerobic conditions to obtain dibenzothiadiazole compound (A) (II). Tetrahydrofuran is added to dibromothiophene compound of formula (V), cooled, n-butyl lithium is added to resulting mixture, tributyl tin hydride is added, and heated, to obtain tributyl tin derivative (B) (III).