TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The 5,15-dibromo-10,20-alkyl carbazole porphyrin is prepared by using another catalyst, an oxidizer and another solvent. Carbazole derivative of formula (D1), another carbazole derivative with formula (D2) and a dipyrromethane of (D3) are dissolved into the latter organic solvent in the presence of the latter catalyst at 20-100 degrees C, where the latter catalyst is propionic acid, trifluoroacetic acid, the oxidizer is dichloro-dicyan benzoquinone, and the latter organic solvent is trichloromethane and dichloromethane. The mixture is reacted for 1-24 hours for obtaining 10,20-alkyl carbazole porphyrin with formula (D4), where the mole ratio of the former carbazole derivative to the latter carbazole derivative to the dipyrromethane is 1:0.1-100: 0.1-100. The 10,20-alkyl carbazole porphyrin is reacted with brominating agent for 1-72 hours at 0-120 degrees C to obtain the 5,15-dibromo-10,20-alkyl carbazole porphyrin, where mol use ratio of the 10,20-alkyl carbazole porphyrin to the brominating agent is 1: 2-1: 5. The (4,4,5,5-tetramethyl-1,3,2-dioxa pentaborane)substituted 3,6-di-parabromobenzene pyrrolopyrrole dione is prepared by adding 3,6-di-para-bromobenzene pyrrolopyrrole dione of formula (E1) and Potassium Carbonate into dimethyl amide. The mixture is heated up to 100-140 degrees C. The mixture is added into borane in batches via an injector. The temperature is kept at 100-140 degrees C for reacting for 12-54 hours. The mixture is cooled to room temperature. The mixture is poured into water, after reacting for 0.5-2 hours to obtaining alkyl substituted 3,6-di-para-bromobenzene pyrrolopyrrole dione of formula (E2). The alkyl substituted 3,6-dipara-bromobenzene pyrrolopyrrole dione is added into anhydrous tetrahydrofuran, ether or dioxane under a mixed low-temperature environment of liquid nitrogen and isopropanol. The mixture is cooled to -78 degrees C, and dripped into n-butyl lithium. The mixture is reacted for 1-3 hours at minus 78 degrees C and consequently added into 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxa-pentaborane. The mixture is reacted for 0.5-2 hours at minus 78 degrees C. The mixture is naturally heated up to room temperature. The mixture is reacted for 6-36 hours to obtain (4,4,5,5-tetramethyl-1,3,2-dioxa pentaborane)substituted 3,6-di-para-bromobenzene pyrrolopyrrole dione Preferred Components: The brominating agent is tetrahydrofuran solution of N-bromosuccinimide, chloroform solution of N-bromosuccinimide, dimethyl amide solution of N-bromosuccinimide or orthodichlorobenzene solution of Nbromosuccimide.