TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The catalyst is either tetrakis(triphenylphosphine)palladium or bis(triphenylphosphine)palladium dichloride, or organopalladium or a mixture of organopalladium to organophosphine ligand. The molar ratio of catalyst to (II) is 0.0001-0.05:1. The molar ratio of the organopalladium to organophosphine ligand is 1:2-1:20. The organopalladium is tris(dibenzylideneacetone)dipalladium(0). The organophosphine ligand is tri(o-methylphenyl)phosphine.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): The preparation of (I) comprises adding substituted 2,8-dibromo-1,4,9-trithia-trindene compounds of formula (II) and substituted 5,8-bis-(5-trimethylstannanyl-thiophen-2-yl)-2H-6,7-dithia-1,2,3-triaza-trindene compounds of formula (III) in a molar ratio of 1:1.1 to an organic solvent under an inert atmosphere, dissolving, then adding a catalyst, then performing Stille coupling reaction at 60-120 degrees C for 24-72 hours, separating and purifying to obtain (I). Preferred Method: The method comprises distilling off excess solvent in the resultant reaction solution after Stille coupling reaction, adding methanol, sedimenting the reaction solution, filtering, washing with methanol, drying, eluting through alumina column chromatography and chloroform, removing solvent by evaporation, settling the methanol, filtering, performing Soxhlet extraction of the resultant solid using acetone, settling the methanol, and filtering to obtain (I). The preparation method of (II) comprises: (a) dissolving 2,3-dibromo-thiophene and alkanoyl chloride in 2-dichloroethane at 0 degrees C in an ice-salt bath to obtain a mixed solution, dropwisely adding dichloromethane solution of aluminum trichloride to the mixed solution, stirring at 0 degrees C for 2 hours, then pouring into 2mol/l ice-hydrochloric acid to quench the reaction, extracting the obtained reaction solution with ether, combining the organic phases, drying the organic phase via anhydrous magnesium sulfate, and evaporating solvent to obtain 2,3-dibromo-5-alkanoyl thiophene, where the molar ratio of 2,3-dibromo-thiophene to alkanoyl chloride is 1:1.1, the molar concentration of 2,3-dibromo-thiophene in the mixed solution is 0.5 mol/l, and the molar concentration of aluminum trichloride in dichloromethane solution of aluminum trichloride is 1.3 mol/l; (b) dissolving the 2,3-dibromo-5-alkanoyl thiophene, 3-thienyl boronic acid, sodium carbonate in mixed solvent comprising distilled water, ethanol and toluene under anaerobic conditions, and then adding tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3)4)catalyst, refluxing for 20 hours at 90 degrees C, cooling to room temperature, and quenching the reaction with distilled water to obtain a mixture, extracting the mixture with ether, drying the combined organic phases over anhydrous magnesium sulfate, filtering, distilling excess solvent by rotary evaporation, separating and purifying by silica gel column chromatography to obtain crude product, eluting the crude product with toluene, and re-crystallizing using toluene/methanol to obtain 5-alkanoyl-2,3-bis(3-thienyl)thiophene, where the molar ratio between 2,3-dibromo-5-alkanoyl thiophene, 3-thienyl boronic acid and sodium carbonate is 1:2.5:10, the volume ratio of distilled water, ethanol and toluene is 1:1:1, the total concentration of 2,3-dibromo-5-alkanoyl thiophene, 3-thienyl boronic acid and sodium carbonate in mixed solvent is 10.2 mol/l, and the molar amount of Pd(PPh3)4 catalyst is 0.02 times the molar amount of 2,3-dibromo-5-alkanoyl thiophene; (c) dissolving the 5-alkanoyl-2,3-bis(3-thienyl)thiophene in dichloromethane at 0 degrees C in ice-salt bath, and followed by adding 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and boron trifluoride etherate to obtain a mixed solution, gradually warming the mixed solution to 30 degrees C for 12 hours, quenching the reaction by adding zinc powder and methanol, stirring overnight, filtering the reaction mixture, extracting the filtrate with dichloromethane, combining organic phases, drying the organic phase via anhydrous magnesium sulfate, filtering, distilling excess solvent by rotary evaporation, and separating by silica gel column chromatography to obtain a crude product, eluting the crude product with toluene and re-crystallizing using ethanol to obtain 5-alkanoyl-benzo(1,2-b:3,4-b':5,6-d'')trithiophene, where the molar volume ratio of 5-alkanoyl-2,3-bis(3-thienyl)thiophene to dichloromethane is 1 mmol:36 ml, the molar ratio of 5-alkanoyl-2,3-di(3-thienyl)thiophene, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and boron trifluoride etherate is 5:6:6.5. and the molar ratio of zinc and 5-alkanoyl-2,3-bis(3-thienyl)thiophene is 0.01:1; and (d) dissolving the 5-alkanoyl-benzo(1,2b:3,4-b':5,6-d'')trithiophene and N-bromosuccinimide in N,N-dimethylformamide under anaerobic and dark conditions, then warming to 50 degrees C for 12 hours, cooling to room temperature, quenching the reaction solution with distilled water, extracting the organic phase with chloroform, washing the organic phase with saturated sodium thiosulfate, drying over magnesium sulfate, filtering, distilling excess N,N-dimethylformamide by rotary evaporation, separating by silica gel column chromatography to obtain crude product, eluting the crude product with toluene, and re-crystallizing from toluene and methanol to obtain (III), where the molar ratio of 5-alkanoyl-benzo(1,2-b:3,4-b':5,6-d'')trithiophene to N-bromosuccinimide is 1:2.5, and the molar volume ratio of 5-alkanoyl-benzo(1,2-b:3,4-b':5,6-d'')trithiophene to N,N-dimethylformamide is 1 mmol:40 ml. Preferred Components: The inert gas in the inert gas atmosphere is nitrogen and/or argon. The organic solvent is tetrahydrofuran, N,N-dimethylformamide or toluene.