TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: n-Type organic semiconductor compound is fullerene or substituted fullerene.    TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Monomer (VIa)-(VIc) and 1 or more monomers chosen from monomers of formula: R7-(Ar1)a-Ac-(Ar2)c-R8 (VIII), R7-Ar1-R8 (IX), R7-Ar3-R8 (X), and R7-Da-R8 (XI) are subjected to aryl-aryl coupling reaction to obtain polymer containing having structural unit (I). Preferred Composition: The polymer further comprises aryl group-containing units of formula: -((Ar1)a-(U')b-(Ar2)c-(Ar3)d)- (IIa), -((U')b-(Ar1)a-(U')b-(Ar2)c-(Ar3)d)- (IIb), -((Ar1)a-(Ac)b-(Ar2)c-(Ar3)d)- (IIIa) or -((Ac)b-(Ar1)a-(Ac)b-(Ar2)c-(Ar3)d)- (IIIb). The polymer is of formula: -((A)x-(B')y-(C')z)n- (IV), or preferably of formula (IV-1). The mixture or polymer blend further comprises polymers and 1 or more n-type organic semiconductor compounds.U'=unit (I);Ar1-Ar3=aryl or heteroaryl (excluding U') (both optionally substituted by group Rs);Rs=F, Br, Cl, CN, NC, -NCO-, -NCS, -OCN, -SCN, -C(O)NR0R00, -C(O)X0, -C(O)R0, -NH21-, NR0R00-, -SH, -SR0, -SO3H, -SO2R0, -OH, -NO2, -CF3, -SF5, silyl, carbyl or 1-40C hydrocarbyl;R0,R00=H, or 1-40C carbyl or hydrocarbyl (both optionally substituted);X0=F, Cl or Br;a,b,c=0,1 or 2;d=1-10;Ac=aryl or heteroaryl (excluding Ar1);A,B',C'=unit of formula (I), (IIa), (IIb), (IIIa) or (IIIb);x=0-1 (excluding 0);y,z=0-1 (excluding 1);x+y+z=1;n=more than 1;Da-Df=groups chosen from groups of formulae (D1)-(D5);andi,m,o,p,q,r=more than 0 to less than 1. EXAMPLE - Nitrogen gas was bubbled to mixture of benzo(1,2-b:4,5-b')-di-(2-bromo(4,4-bis-(4-hexadecylphenyl)-4H-cyclopenta(2,1)dithiophen-2-yl)) (300 mg), 2,5-bis-trimethylstannanyl-thieno(3,2-6)thiophene (83.4 mg), and tri-o-tolyl-phosphine (18) in anhydrous toluene for 30 minutes. Tris(dibenzylideneacetone)dipalladium(0) (11.3 mg) was added to the reaction mixture, heated, bromobenzene was added, heated and tributyl-phenyl-stannane was added. The mixture was heated, cooled and the polymer precipitate was collected by filtration. The crude polymer was subjected to Soxhlet extraction using acetone, petrol, cyclohexane and chloroform. The chloroform extract was poured into methanol and the polymer precipitate was filtered to obtain light brown solid of poly(2,9-(6,12-dihydro-6,6,12,12-tetrakis(4-(hexadecyl)phenyl))-indeno(1,2-b)indeno(2',4':4,5)thieno(2,3-d)thiophene-alt-(2,5-thieno-(3,2-b)thiophene)) with yield of 74%. The obtained polymer has number-average molecular weight of 97000 g/mol and weight-average molecular weight of 238000 g/mol.