TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The organic semiconductor material is in the form of a composite comprising a substrate, where a thin film semiconductor comprising the copolymer is deposited on the substrate. The copolymer (A) is of formula (-(A1)v-(B1)w-). Copolymer (A) is substituted polythiophenyl compounds of formula (IVa)-(IVd). The copolymer (A) has a weight average molecular weight of 5000-200000, preferably 10000-120000.v, w = 4-1000, preferably 4-200; andn = 4-300, preferably 10-200. Preferred Definitions:    G1-G5 = H (preferred), F, 1-25C alkyl, phenyl, naphthyl, 1-12C alkylphenyl (optionally substituted by at least one F, -CN, phenyl, naphthyl);    R1, R2 = 1-35C alkyl or 8-35C alkyl, phenyl or 1 or 2-naphthyl;    R99, R104, R104a, R105, R105a = F, or 7-25C phenylalkyl; and    R107 = phenyl or naphthyl.    EXAMPLE - To a cooled (-78 degrees C) solution of benzo(1,2-b,4,3-b)dithiophene (1.05 g) in dry tetrahydrofuran (20 ml) was added to butyl lithium (4.5 ml). The resulting solution was stirred for 15 minutes at 0 degrees C and cooled to -78 degrees C. 2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxoborolane (5.2 g) was added dropwise, kept for 5 minutes at -78 degrees C, then the solution was slowly warmed and stirred for 30 minutes. The reaction was quenched by adding hydrochloric acid (50 ml, 10%) and the product was extracted twice with ethyl acetate (40 ml). The combined organic extracts were dried and evaporated and purified to give 2,7-bis(4,4,5,5-tetramethyl-(1,3,2)dioxaborolan-2-yl)-benzo(1,2-b,4,3-b)dithiophene (compound-14, 1.77 g). 3,6-Bis(5-bromothiophen-2-yl)-2,5-bis(2-decyltetradecyl)pyrrolo(3,4-c)pyrrole-1,4(2H,5H)-dione (compound-15, 1.25 g), compound-14 (0.51 g), palladium(acetate) (7.4 g) and 2-(di-tert-butyl-phosphino)-1-phenyl-pyrrole were mixed with tetrahydrofuran (55 ml) and warmed to 60 degrees C. Then a solution of lithium hydroxide (0.29 g) was added to the reaction mixture and worked up to give poly-2,5-bis-(2-decyl-tetradecyl)-3-(5-(7-methyl-benzo(1,2-b,4,3-b)dithiophen-2-yl)-thiophen-2-yl)-6-(5-methyl-thiophen-2-yl)-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione (1.04 g).