TECHNOLOGY FOCUS - POLYMERS - Preparation (Claimed): Preparation of (I) comprises coupling one or more monomers with one or more thiophene monomers of formula (V) in an aryl-aryl coupling reaction. Preferred Components: (I) is of formula (-((A)x-(B1)y)n-) (II) or (R8-chain-R9) (III). 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.A1 = (I) or its subformulae (Ia)-(Ik), (Im) and (In);B1 = a unit that is different from A, and either (I) or (Ia)-(Ik), (Im) and (In), or aryl or heteroaryl (both optionally substituted); eitherx = greater than 0 to less than or equal to 1; andy = greater than or equal to 0 to smaller than 1; orx+y = 1; andn = greater than 1;chain = a polymer chain of formulae (II) or (IIa)-(IIj) and (IIm)-(IIr);R8, R9 = H, F, Br, Cl, I, -CH2Cl, -CHO, -CRa1=CRb12, -SiRa1Rb1Rc1, -SiRa1XaXb, -SiRa1Rb1Xa, -SnRa1Rb1Rc1, -B1Ra1Rb1, -B1(ORa1)(ORb1), -B1(OH)2, -O-SO2-Ra1, -CCH, -CC-SiRa13, -ZnXa or an endcap group;Xa, Xb = halo; andRa1, Rb1, Rc1 = R1a, where two of Ra1-Rc1 optionally form a ring together with the heteroatom to which they are attached. EXAMPLE - Mixture of a distannyl monomer (1.49 g), 4,7-bis-(5-bromo-4-hexyl-thiophen-2-yl)-benzo(1,2,5)thiadiazole (595 mg), bis(dibenzylideneacetone)palladium(0) (30 mg) and tri-o-tolylphosphine (70 mg) were placed in a two-necked flask, and treated with evacuation-argon cycle three times. Anhydrous toluene (200 cm3) was added to the reaction mixture via a syringe and the reaction flask was again treated with evacuation-argon cycle three times. The reaction mixture was then heated to 110 degrees C for 72 hours. After cooling to 60 degrees C, an aqueous solution of sodium diethylthiocarbamate trihydrate (15 mg in 200 cm3 of water) was added to the reaction mixture and the mixture was stirred at 90 degrees C for 18 hours. The resulting solution was washed three times with water and the organic layer was poured into methanol (500 cm3) for precipitation and worked up to obtain 7H-3,4-dithia-7-sila-cyclopenta(a)pentalene units compound of formula (Iaa) (126 mg) as a black solid.