TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Preparation of the polymer comprises coupling one or more monomers (VIa) or (VIb) (where R7 and R8 are Cl, Br, I, -B(OZ2)2 or -Sn(Z4)3), with each other and/or with one or more monomers of formulae (R7-(Ar1)a-D1-(Ar2)c-R8) (VIII), (R7-AR1-R8) (IX) and (R7-AR3-R8) (X) in an aryl-aryl coupling reaction. Preferred Components: The polymer comprises one or more units of formula -((Ar1)a-(U1)b-(Ar2)c-(Ar3)d)- (IIa) or -((U1)b-(Ar1)a-(U1)b-(Ar2)c-(Ar3)d)- (IIb). The polymer additionally comprises one or more repeating units of formula -((Ar1)a-(D1)b-(Ar2)c-(Ar3)d)- (IIIa) or -((D1)b-(Ar1)a-(D1)b-(Ar2)c-(Ar3)d)- (IIIb). The polymer is formulae -((Ar1-U1-Ar2)x-(Ar3)y)n- (IVa), -((Ar1-U1-Ar2)x-(Ar3-A32)y)n- (IVb), -((Ar1-U1-Ar2)x-(Ar3-Ar3-Ar3)y)n- (IVc), -((Ar1)a-(U1)-b-(Ar2)c-(Ar3)d)n- (IVd), -(((Ar1)a-(U1)-b-(Ar2)c-(Ar3)d)x-((Ar1)a-(D1)-b-(Ar2)c-(Ar3)d)y)n- (IVe), -((U1Ar1-U1)x-(Ar2-Ar3)y)n- (IVf), -((U1-Ar1-U1)x-(Ar2-Ar3-Ar3)y)n- (IVg), -((U1)b-(Ar1)a-(U1)b-(Ar2)c)n- (IVh), -(((U1)b-(Ar1)a-(U1)b-(Ar2)c)x-((D1)b-(Ar1)a-(D1)b-(Ar2)d)y)n- (IVi), -((U1-Ar1)x-(U1-Ar2)y-(U1-Ar3)z)n- (IVk). The polymer is of formula R5-chain-R6 (V) or a small molecule of formula (Rt1-(Ar4)e-(Ar5)f-((Ar6)g-(Ar7)h-U1-(Ar8)i-(Ar9)k)p-(Ar10)l-(Ar11)o-Rt2) (VII), and has a molecular weight of at least 5000-300000. The mixture or polymer blend comprises one or more polymers and one or more n-type organic semiconductor compounds. The n-type organic semiconductor compound is a fullerene or substituted fullerene.Ar1-Ar3 = aryl or heteroaryl that is different from U1, has 5-30 ring atoms and is optionally substituted by one or more Rs;Rs = F, Br, Cl, -CN, -NC, -NCO, -NCS, -OCN, -SCN, -C(O)NR0R00, -C(O)X0, -C(O)R0, -NH2, -NR0R00, -SH, -SR0, -SO3H, -SO2R0, -OH, -NO2, -CF3, -SF5, optionally substituted silyl, carbyl or hydrocarbyl with 1-40C atoms that is optionally substituted and optionally comprises one or more hetero atoms;X0 = halo, preferably F, Cl or Br;a, b, c = 0, 1 or 2;d = 0 or 1-10, where b is at least 1;D1 = aryl or heteroaryl that is different from U and Ar1-Ar3, has 5-30 ring atoms, is optionally substituted by one or more Rs and is selected from aryl or heteroaryl having electron donor properties;chain = a polymer chain of (IV) or (IVa)-(IVk);R5, R6 = R1 or H, F, Br, Cl, I, -CH2Cl, -CHO, -CR1=CR2a, -SiR1R2R3, -SiR1X1X2, -SiR1R2X1, -SnR1R2R3, -BR1R2, -B(OR1)(OR2), -B(OH)2, -O-SO2-R1, -C=CH, -C=C-SiR3a, -ZnX1 or an endcap group;X1, X2 = halo; andR1-R3 = R0, where two of R1, R2 and R3 form a ring together with the hetero atom to which they are attached.In formula (VII),Ar4-Ar12 = -CY1=CY2-, -C=C- or aryl or heteroaryl that has 5-30 ring atoms and is optionally substituted by one or more groups R1, where and one or more of Ar4-Ar12 = U1;Y1, Y2 = H, F, Cl or CN;Rt1, Rt2 = H, F, Cl, Br, -CN, -CF3, R, -CF2-R, -O-R, -S-R, -SO2-R, -SO3-R-C(O)-R, -C(S)-R, -C(O)-CF2-R, -C(O)-OR, -C(S)-OR, -O-C(O)-R, -O-C(S)-R, -C(O)-SR, -S-C(O)-R, -C(O)NRR1, -NR1-C(O)-R, -NHR, -NRR1, -CR1=CR2R3, -C=C-R1, -C=C-SiR1R2R3, -SiR1R2R3, -CH=C(CN)-C(O)-OR, -CH=C(COOR)2, CH=C(CONRR1)2, CH=C(CN)(Ar12) or monovalent groups of formulae (aa)-(ae);R1a, R1b = aryl or heteroaryl, each having 4-30 ring atoms and being optionally substituted with one or more R or R1;Ar12 = aryl or heteroaryl, each having from 4 to 30 ring atoms and being optionally with one or more R1;R = straight-chain, branched or cyclic 1-30C-alkyl (optionally substituted with one or more F or Cl) or CN groups, or perfluorinated and in which one or more C atoms are optionally replaced by -O-, -S-, -C(O)-, -C(S)-, -SiR0R00-, -NR0R00-, -CHR0=CR00- or -C=C- such that O- and/or S-atoms are not directly linked to each other;R1-R3 = R or H;e, f, g, h, i, k, l, o = 0 or 1, where at least one of e, f, g, h, i, k, l, o is 1; andp =1, 2 or 3. Preferred Definitions:    D1 = 63 divalent groups of formulae e.g. (b1)-(b10);    R11-R18 = H or one of R1; and    Ar1-Ar3 = 76 heteroaryl compounds e.g. thiophene moiety, 3-(2-ethyl-hexyl)-thiophene moiety, 4,8-bis-(2-ethyl-hexyloxy)-2,6-dimethyl-benzo(1,2-b,4,5-b')dithiophene moiety, 4,8-bis-(1-nonyl-decyloxy)-benzo(1,2-b,4,5-b')dithiophene moiety, 4,8-bis-(1-tridecyl-tetradecyloxy)-benzo(1,2-b,4,5-b')dithiophene moiety, 4,8-bis-dodecyloxy-benzo(1,2-b,4,5-b')dithiophene moiety, 4-dodecyloxy-8-tridecyl-benzo(1,2-b,4,5-b')dithiophene moiety, 5,6-bis-octyloxy-benzo(1,2,5)thiadiazole moiety, thiazolo(5,4-d)thiazole moiety, 1,2,4,5-tetrazine moiety, (1,2,5)thiadiazolo(3,4-d)pyridazine moiety, (1,2,5)thiadiazolo(3,4-d)pyridazine moiety, (1,2,5)oxadiazolo(3,4-d)pyridazine moiety, (1,2,5)selenadiazolo(3,4-d)pyridazine moiety, 1,2,6-thiadiazin-4-one moiety or thieno(3,2-b)thiophene-2,5-dione moiety.    SPECIFIC COMPOUNDS - 8 compounds (I) are specifically claimed e.g. 1,2,5,6-tetrahydro-(1,5)naphthyridine moiety of formulae (Ia)-(Ie).    EXAMPLE - 128.1 mg of 3,7-Bis-(5-bromo-4-(2-ethyl-hexyl)-thiophen-2-yl)-1,5-dimethyl-1,5-dihydro-(1,5)naphthyridine-2,6-dione, 71.3 mg of 2,5-bis-trimethylstannanyl-thiophene and 3.7 mg of bis(triphenylphosphine)palladium(II) dichloride were added to a dry microwave vial. The vial was evacuated and nitrogen purged and then degassed toluene (4 cm3) and degassed N,N-dimethylformamide (1 cm3) were added. The solution was degassed for 1 hour before heating to 110 degrees C for 2 hours and further heated in a microwave reactor at 140 degrees C for 1 minute, 160 degrees C for 1 minute and 170 degrees C for 30 minutes. The reaction mixture was precipitated into methanol and collected by filtration to yield 77 mg of poly-3,7-bis-(4-(ethyl-hexyl)-thiophen-2-yl)-1,5-dimethyl-1,5-dihydro-(1,5)naphthyridine-2,6-dione-thiophene as dark blue polymer.