TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparation of the polymer comprises coupling the monomer with each other and/or with at least one monomer comprising R7-(Ar1)a-A1c-(Ar2)c-R8 (c1), (R7-Ar1-R8) or (R7-Ar3-R8) in an aryl-aryl coupling reaction.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The polymer comprises at least one unit of formula (-((Ar1)a-(U1)b-(Ar2) c-(Ar3)d)-) (II).U1 = is a unit of (I);Ar1-Ar3 = 5-30C aryl or 5-30C heteroaryl ring (both optionally substituted by at least one R1s) (where Ar1, Ar2 is preferably e.g. 1,3,4-thiadiazole-2,5-diyl, 2,3-dihydrothieno(3,4-b)(1,4)dioxine-5,7-diyl, substituted thiophene moiety of formula (a1), substituted 1,3-thiazolemoiety of formula (a2), substituted 1H-silole moiety of formula (a3), substituted furan moiety of formula (a4), substituted selenophene moiety of formula (a5), substituted 1H-pyrrole moiety of formula (a6), substituted thieno(3,2-b)thiophene moiety of formula (a7) or substituted thieno(2,3-b)thiophene moiety of formula (a8) and Ar3 is preferably e.g. (a1)-(a8), (1,2,5)thiadiazolo(3,4-d)pyridazine-4,7-diyl, (1,2,5)oxadiazolo(3,4-d)pyridazine-4,7-diyl, (1,2,5)selenadiazolo(3,4-d)pyridazine-4,7-diyl, furo(3,2-b)furan-2,5-dione-3,6-diyl, thieno(3,2-b)thiophene-2,5-dione-3,6-diyl, cyclobut-3-ene-1,2-dione-3,4-diyl, 1,4-difluoro-benzene-2,5-diyl, 1,3,4-trifluoro-benzene-2,5-diyl or 1,2,4,5-tetrafluoro-benzene-3,6-diyl);R11-R13 = H;R1s = 1-40C silyl, carbyl or hydrocarbyl (all optionally substituted by at least one hetero atom), F, Br, Cl, -CN, -NC, -NCO, -NCS, -OCN, -SCN, -C(O)NR20R210, C(O)X10, -C(O)R20, -NH2, -NR20R210, -SH, -SR20, -SO3H, -SO2R20, -OH, -NO2, -CF3 or -SF5;R20, R210 = 1-40C carbyl or 1-40C hydrocarbyl (both optionally substituted) or H;X10 = halo, preferably F, Cl or Br;a-c = 0-2 (where b is at least 1); andd = 1-10.The polymer additionally comprises at least one repeating unit of formula (-((Ar1)a-(A1c)b-(Ar2) c-(Ar3)d)-) (III).A1c = aryl or heteroaryl group that is different from U1 and Ar1-Ar3 and has 5-30 ring atoms optionally substituted by R1s and is aryl or heteroaryl having electron acceptor properties (where A1c is preferably e.g. (1,2,5)thiadiazolo(3,4-d)pyridazine-4,7-diyl, (1,2,5)oxadiazolo(3,4-d)pyridazine-4,7-diyl, (1,2,5)selenadiazolo(3,4-d)pyridazine-4,7-diyl, furo(3,2-b)furan-2,5-dione-3,6-diyl, thieno(3,2-b)thiophene-2,5-dione-3,6-diyl, cyclobut-3-ene-1,2-dione-3,4-diyl, 1,4-difluoro-benzene-2,5-diyl, 1,3,4-trifluoro-benzene-2,5-diyl or 1,2,4,5-tetrafluoro-benzene-3,6-diyl).The polymer is e.g. substituted compounds of formula ((A)x1-(B6a)y1)n1 (IV), (-(((Ar1)-U1-(Ar2))x1-((Ar2)-(Ar3))y1)n1-) (IV), (-(((Ar1)-U1-(Ar2))x1-((Ar2)-(Ar3))y1)n1-) (IV) (-((Ar1)a-U1b-(Ar2)c-Ar3d)n1) or R5-chain-R6 (V).B6a = aryl or heteroaryl (both optionally substituted);x1 = greater than 0 to less than or equal to 1;y = greater than or equal to 0 to less 1;x+y = 1;n = greater than 1;chain = polymer chain of (IV);R5, R6 = H, halo, -CH2Cl, -CHO, -CR1q=CR11q2, -SiR1qR11qR111q, -SiR1qX1qX11q, -SiR1qR11qX1q, -SnR1qR11qR111q, -BR1qR11q, B(OR1q)(OR11q), -B(OH)2, -O-SO2-R1q, -CCH, -CC-Si(R1q)3, -ZnX1q or an end cap group; eitherR1q, R11q, R111q = R10; ortwo of R1q, R11q, R111q+hetero atom = ring; andX1q, X11q = halo.The monomer is substituted compounds of formula (R7-Ar1-U1-Ar2-R8) (VIa), (R7-U1-R8) (VIIa), (R7-Ar1-U1-R8) (VIIIa) or (R7-U1-Ar2-R8) (VIIb). The mixture or polymer blend comprises (I) and at least one n-type organic semiconductor compounds. The n-type organic semiconductor compound is optionally substituted fullerene. EXAMPLE - Nitrogen gas was bubbled through a mixture of 200 mg 2,20-dibromo-(6,12-dihydro- 6,6,12,1 2-tetrakis(4-dodecylphenyl)-1,7-dithia-dicyclopenta(a, h)indeno(1,2-b)fluorene and 65.5 mg 5,5'-bis- trimethylstannanyl-(2,2')bithiophenyl in 2 cm3 anhydrous toluene and 0.5 cm3 anhydrous N,N-dimethylformamide for 1 hour. 4.9 mg Tris(dibenzylideneacetone)dipalladium(0), and 6.5 mg tri-o-tolyl-phosphine were added to the reaction mixture followed by heating at 120 degrees C for 65 hours. The reaction mixture is poured into 100 cm3 methanol and polymer precipitate was collected by filtration. The crude polymer was subjected to sequential Soxhlet extraction, methanol, acetone, 40-60 petroleum, 80-1 00 petroleum, cyclohexane, chloroform and chlorobenzene. The chlorobenzene extract was poured into 200 cm3 methanol and the polymer precipitate was collected by filtration to give poly(2,20-(6,12-dihydro-6,6,12,12-tetrakis(4-dodecylphenyl)-1,7-dithiadicyclopenta(a,h)-indeno(1,2-b)fluorene))-alt-(2,2'bithiophene) (75%).