TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Device: The semiconductor device (S1) is a photovoltaic device that comprises the following components in order: (a) a cathode (electrode), (b) optionally a transition layer (comprising an alkali halogenide, especially lithium fluoride), (c) a photoactive layer, (d) optionally a smoothing layer, (e) an anode (electrode), and (f) a substrate.    TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Preparation of the copolymer of formula -(A1-D1)-(B1-D1)- (VIII) involves reacting a dihalogenide (preferably dibromide, dichloride or diiodide, especially dibromide) of formula Br-A1-Br or Br-B1-Br with an equimolar amount of diboronic acid or diboronate of formula X11-D1-X11 in a solvent and in presence of a catalyst.X11=-B(OH)2, -B(OY1)2, or group of formula (xix) or (xx);Y1=1-10C alkyl;Y2=2-10C alkylene (preferably -CY3Y4-CY5Y6-, or -CY7Y8-CY9Y10-CY11Y12-;Y3-Y12=H, or 1-10C alkyl (preferably -C(CH3)2C(CH3)2-, -C(CH3)2CH2C(CH3)2-, or -CH2C(CH3)2CH2-;Y13 and Y14=H, or 1-10C alkyl.Preferred Compounds: The polymer (P1) is selected from 20 compounds as given in the specification, e.g. a compound of formula (Ia).R24a=8-38C alkyl;R26a=1-18C alkyl (preferably 4-18C alkyl);n=4-1000 (preferably 4-200, especially 5-100). Preferred Definitions:    R1 and R2=branched 8-36C alkyl;    R3=4-18C alkyl.    EXAMPLE - To a degassed solution of 3,6-bis-(5'-bromo-4'-hexyl-(2,2')bithiophenyl-5-yl)-2,5-bis-(2-hexyl-decyl)-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione (2 g), 5,5'-dibromo-3,3'-dihexyl-(2,2')bithiophenyl (0.17 g), 2,5-thiopheneboronic acid bis(pinacol) ester (0.68 g), tri-tert-butylphosphonium tetrafluoroborate (30 mg) and tris(dibenzylideneacetone) dipalladium(0) (46 mg) in tetrahydrofuran (20 ml), a solution of potassium phosphate (1.28 g) in water (5 ml) was added. The reaction mixture was heated to reflux for two hours. Subsequently, bromo-thiophene (16 mg) was added, stirred for 20 minutes, and thiophene-boronic acid pinacol ester (21 mg) was added to stop the polymerization reaction. The reaction mixture was cooled to room temperature and precipitated in methanol. The residue was purified by extraction to obtain a polymer (1.1 g) as a dark powder having molecular weight (M. wt. 40000), and polydispersity of 1.7.