TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): 2,1,3-Benzothiadiazole-based thiophene-conjugated polymer derivative (I) is prepared by dissolving carbazole-borate in tetrahydrofuran solution, and then n-butyl lithium solution is mixed into it to obtain mixed solution. The mixed solution is stirred at 78 degrees C for 0.5 hours and cooled at room temperature for 0.5-3 hours to obtain cooled product. The cooled product is mixed with trimethyltin chloride in heated n-butyl lithium solution under presence of inert gas, and then heated at room temperature for 1-12 hours to obtain pure organotin compound. Organotin compound is reacted with conjugated polymer of benzothiadiazole and di-thiophene, and then frozen in liquid nitrogen, where air is discharged. Catalyst is added in presence in frozen product under inert gas, and heated at 105-115 degrees C for 40-50 hours to obtain product. The product is cooled to room temperature to obtain liquid, and then purified to obtain the desired product. Preferred Process: Conjugated polymer is mixed in water/n-hexane or water/ethyl acetate solvent. Organic phase is dried in presence of magnesium sulfate or sodium sulfate, then organic phase is evaporated to remove organic solvent. Organic phase is purified in the column chromatography and then recrystallized by using isopropanol or ethanol solvent as mobile phase, where alkaline aluminum oxide is used as a stationary phase, and n-hexane is used as an eluent. Organotin compound is mixed with 2,1,3-benzothiadiazole and dibromo-bithiophene in ratio of 1:1:1. Preferred Components: Catalyst is tetrakis(triphenylphosphine) palladium or tris(dibenzylideneacetone)dipalladium. n-Butyllithium solution is selected from tetrahydrofuran solution of n-butyllithium or n-butyllithium hexane solution. Trimethyltin chloride solution is selected from trimethylsilyl chloride or tetrahydro furan solution of n-hexane solution of trimethyl tin or tin chloride. Preferred Conditions: Organic material, n-butyllithium and trimethyltin chloride are mixed in the ratio of 2:5:6.