TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Monomer(s) are coupled with each other and/or with monomer of formula: R2-Ar3-R3 (A) to obtain the polymer. Preferred Component: The polymer further contains repeating unit of formula: -((Ar1)a-(U')b-(Ar2)c-(Ar3)d)- (II), -((Ar1)a-(M)b-(Ar2)c(Ar3)d)- (III), -((A)x(B')y)n- (IV), -((Ar1)a-(U')b-(Ar2)c-(Ar3)d)n- (IIIa), -(((Ar1)a-(U')b-(Ar2)c-(Ar3)d)x-((Ar1)a(M)b-(Ar2)c-(Ar3)d)y)n- (IIIb) and R2-((A)x(B')y)n-R3 (IV). The polymer is chosen from 26 polymers e.g. polymers of formulae (i)-(v).X'=halo, preferably F, Cl or Br;a-d=0, 1 or 2;M=aryl or 5-30C heteroaryl optionally substituted by R;A=U' or group of formula (II);B'=unit comprising aryl or heteroaryl;x,y=0-1;x+y=1;n=more than 1;andRb',Rb",Rb'",Rc',Rd',Re',Rf',Rg'=R1. Preferred Definitions:    Ar1,Ar2=thiophen-2,5-diyl, thiazol-2,5-diyl, selenophen-2,5-diyl, furan-2,5-diyl, thieno(3,2-b)thiophen-2,5-diyl, thieno(2,3-b)thiophen-2,5-diyl, selenopheno(3,2-b)selenophen-2,5-diyl, selenopheno(2,3-b)selenophen-2,5-diyl, selenopheno(3,2-b)thiophen-2,5-diyl, or selenopheno(2,3-b)thiophen-2,5-diyl (all optionally substituted 1 or more substituents);    Ar1,Ar2=single bond;and    Ar3=1,4-phenylene, 2,3-dicyano-1,4-phenylene, 2,5-dicyano, 2,3-difluoro-1,4-phenylene, 2,5-difluoro-1,4-phenylene, 2,3,5,6-tetrafluoro, 3,4-difluorothiophen-2,5-diyl, pyridin-2,5-diyl, pyrimidin-2,5-diyl, naphthalen-2,6-diyl, thiophen-2,5-diyl, furan-2,5-diyl, selenophen-2,5-diyl, thieno(3,2-b)thiophen-2,5-diyl, thieno(2,3-b)thiophen-2,5-diyl, selenopheno(3,2-b)selenophen-2,5-diyl, selenopheno(2,3-b)selenophen-2,5-diyl, selenopheno(3,2-b)thiophen-2,5-diyl, selenopheno(2,3-b)thiophen-2,5-diyl, benzo(1,2-b:4,5-b')di-thiophen-2,6-diyl, benzo(2,1-b,3,4-b')dithiophen-2,7-diyl, 2,2'-dithiophene, 2,2'-diselenophene, dithieno(3,2-b:2,3'-d)silole-5,5-diyl, dithieno(3,2-b,2,3'-c)pyrrole-5,5- diyl, cyclopenta(2,1:3,4-6')dithiophen-2,6-diyl, carbazol-2,7-diyl, fluoren-2,7-diyl, indaceno(1,2-b:5,6-b')dithiophen-2,7-diyl, benzo(1,2":4,5:4,5":4,5,)bis-silolo(3,2-b:3',2,-b,)thiophen-2,7-diyl, phenanthro(1,10,9,8-c,d,e,f,g)carbazol-2,7-diyl, benzo(2,1,3)thiadiazol-4,7-diyl, benzo(2,1,3)selenadiazol-4,7-diyl, benzo(2,1,3)oxadiazol-4,7-diyl, 2H-benzotriazol-4,7-diyl, quinoxalin-5,8-diyl, thieno(3,4-b)pyrazin-2,5-diyl, thieno(3,4-b)thiophen-4,6-diyl, thieno(3,4-b)thiophen-6,4-diyl, thieno(2,1,3)thiadiazol-2,5-diyl, 2,5-di-thien-2-yl-thieno(2,1,3)thiadiazole, pyrrolo(3,4-c)pyrrole-1,4-dion-3,6-diyl, (1,3)thiazolo(5,4-d)(1,3)thiazol-2,5-diyl, 2,5-di-thien-2-yl-(1,3)thiazolo(5,4-d)(1,3)thiazole, thieno(3,4-c)pyrrole-4,6-dione-1,3-diyl, 4-oxa-1,8-dithia-as-indacene-2,7-diyl, benzo(c)chromene-3,8-diyl (all optionally substituted by 1 or more R1).    EXAMPLE - (In mg) 4,8-didodecyl-2,6-bis-trimethylstannyl-benzo(1,2-b,4,5-b')dithiophene (237.9), 3,6-bis(5-bromo-3-octyl-thiophen-2-yl)thieno(3,2-b)thiophene-2,5-dione (200), palladium catalyst (2.6) and tri-o-tolyl phosphine (3.4) dissolved in degassed toluene and dimethylformamide was polymerized at 180 degrees C. The polymer was precipitated with methanol, and purified to obtain a polymer (188, yield of 62%) with number average molecular weight of 68.4 kg.mol-1 and weight average molecular weight of 185.9 kg.mol-1.