TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation of (I) comprises dissolving 2,6-bis(tributylstannyl)-thieno(2,3-f)(1)benzothiophene compounds of formula (III) and 1,6-dibromo-8,11-dithia-7,9,10,12-tetraaza-dicyclopenta(c,g)phenathrene compounds of formula (IV) at molar ratio of 1:1.5-1.5:1 in an organic solvent under an inert atmosphere, adding catalyst, performing Stille coupling reaction for 6-108 hours at 50-120 degrees C, and then separating and purifying to obtain (I). Preferred Method: The separation and purification process comprises adding de-ionized water and toluene to the reaction solution and performing extraction, vacuum distilling the collected organic phase, and then adding anhydrous ethanol dropwisely, precipitating, filtering the precipitate and drying to obtain a solid powder, dissolving the powder with chloroform, and then performing separation by neutral alumina or silica gel column chromatography using toluene or petroleum ether as eluent, distilling the liquid under reduced pressure, settling of methanol and filtering to obtain solid, performing extraction in a Soxhlet extractor for three days using acetone, then followed by settling of methanol, filtering, and filtering overnight under vacuum to obtain (I). The preparation method of (IV) comprises: (a) reacting 4-nitrobenzene-1,2-diamine with thionyl chloride and pyridine at 80-90 degrees C for 24 hours, and separating to obtain 5-nitro-2,1,3-benzothiadiazole (V), where the molar volume ratio of 4-nitrobenzene-1,2-diamine to thionyl chloride is 1.5:1 mol/ml, and the volume ratio of thionyl chloride to pyridine is 50:1, (b) brominating (V) with hydrobromic acid and liquid bromine at 127 degrees C for 4 hours to obtain 4,7-dibromo-5-nitro-2,1,3-benzothiadiazole (VI), where the mass fraction of hydrobromic acid is 40%, the molar volume ratio of (V) to hydrobromic acid is 4:1 mol/ml and the molar volume ratio of (V) to liquid bromine is 5.3:1 mol/ml, (c) performing coupling reaction of (VI) in presence of copper catalyst at 120 degrees C for 3 hours to obtain 4,4'-dibromo-6,6'-dinitro-linked 2,1,3-benzothiadiazole (VII), where the molar ratio of (VI) to copper catalyst is 0.2:1, (d) reducing nitro group of (VII) using tin dichloride at 100 degrees C for 10 hours, then performing diazotization reaction with sodium nitrite in presence of hydrochloric acid at below 5 degrees C for 30 minutes, and followed by reacting obtained compound with potassium iodide for 12 hours to obtain 4,4'-dibromo-6,6'-diiodo-linked 2,1,3-benzothiadiazole (VIII), where the molar ratio of (VII) to tin dichloride is 1:10, molar ratio of (VII) to hydrochloric acid is 0.92:1, the molar ratio of (VII) to sodium nitrite is 0.53:1 and the molar ratio of (VII) to potassium iodide is 0.054:1, and (e) cyclizing (VIII) with acetylene compounds of formula (R1-C(C)-R2) (IX) in dimethylformamide solvent under anaerobic conditions in presence of tributylamine and palladium acetate catalyst at 130 degrees C for 4 hours to obtain (IV), where the molar ratio of (VIII) to (IX) is 1:2, the cyclization reaction is carried out at 130 degrees C for 4 hours, and the molar ratio of (IX), tributylamine and palladium acetate is 20:20:1. Preferred Components: The preparation of (I) in which, the organic solvent is tetrahydrofuran, ethylene glycol dimethyl ether, dioxane or toluene.