TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The electron-accepting material is fullerene or its derivative(s).    TECHNOLOGY FOCUS - POLYMERS - Preparation (disclosed): Polymer block (B) monomers of formula: Mq1-Y'-Mq1 and Mq2-Z-Mq2 are reacted in presence of polymer block (A)-containing compound of formula: A-X and catalyst, terminal of polymer block (A) and monomer of polymer block (B) or polymer block (B) is combined during polymerization by coupling reaction, to obtain pi -electron conjugation block copolymer.A=polymer block;Y',Z=heteroaryl structure;Mq1,Mq2=halo, boronic acid, boronate, -MgX, -ZnX, -SiX3 or -SnRa'3;Ra'=linear 1-4C alkyl;andX=terminal functional group.Preferred Composition: The polymer block (A) and polymer block (B) contain monomeric unit of formula: -a-b- (M), preferably monomeric unit of formulae (I)-(XI). At least one of polymer blocks (A) and (B) is a random copolymer of monomeric units (M).-a-=group of formulae (a)-(f);-b-=group of formulae (g)-(q);V1=N(-NR1-), -O- or -S-;V2=C(-CR12-), N(-NR1-), Si(-SiR12-) or Ge(-GeR12-);V3=heteroaryl or aryl of formula: -(Ar)n-;V4=N(-NR1-), -O- or -CR2=CR2-;V5=O or S;R1=optionally substituted 1-18C alkyl;R2=H or optionally substituted 1-18C alkyl;R3=optionally substituted 1-18C alkyl or alkoxy;R4=optionally substituted 1-18C alkyl, H, halo or aryl group;R5=optionally substituted 1-18C alkyl, aryl, alkylcarbonyl or alkyloxycarbonyl;V2=C(-CR12-), N(-NR1-), Si(-SiR12-) or Ge(-GeR12-);R6=H or halo;m=1-3;andn=0-3.At least one of -a- and -b- is group of chemical structure having condensed-ring ( pi )-conjugated structure including thiophene ring in one portion. Preferred Property: The pi -electron conjugation block copolymer has number average molecular weight of 1000-200000 g/mol. EXAMPLE - 2,6-Dibromo-4,4'-bis(2-ethylhexyl)-cyclopenta(2,1-b:3,4-b')dithiophene and 4,7-bis(3,3,4,4-tetramethyl-2,5,1-dioxaborolan-1-yl)benzo(c)(1,2,5)thiadiazole were polymerized, to obtain polymer block (A1). 2,6-Dibromo-4,4'-bis(2-ethylhexyl)-dithieno(3,2-b:2',3'-d)silole and 4,7-bis(3,3,4,4-tetramethyl-2,5,1-dioxaborolan-1-yl)benzo(c)(1,2,5)thiadiazole were polymerized, to obtain polymer block (B1). (In g) polymer block (A1) (0.8), polymer block (B1) (0.83), toluene (20 mL), 2 M potassium carbonate aqueous solution (10 mL), tetrakis(triphenylphosphine)palladium(0) (20.5 mg) and Aliquat 336 (RTM: quaternary ammonium salt) (0.8 mg) were added, stirred at 80 degrees C for 24 hours, reaction solution was poured into methanol (200 mL), obtained crude product was dried under reduced pressure, deposited solid was filtered, washed using water (20 mL), methanol (20 mL), acetone (100 mL) and hexane (100 mL), extracted using chloroform (100 mL), obtained solution was poured into methanol (1L), dried under reduced pressure, and deposited solid is filtered, to obtain block copolymer (0.51) having weight average molecular weight of 40800, number average molecular weight of 85200 and polydispersion degree of 2.09.