TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparation of the copolymer comprises (a) contacting each of a 2,5-dihalo-3-alkylthiophene and an unsubstituted 2,5-dihalothiophene respectively, each dissolved in an aprotic solvent, with a metal or an organometallic reagent, where the metal is zinc, magnesium, and/or manganese, or the organometallic reagent comprises zinc, magnesium, and/or manganese to provide respective thienyl organometallic solutions, then combining the respective thienyl organometallic solutions, to provide a mixed thienyl organometallic solution, then, (b) contacting the mixed organometallic solution and a nickel catalyst, to provide the copolymer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The 3-alkylthienyl and the unsubstituted thienyl monomeric units are present in a ratio of 1:99-99:1, or 1:5-50:1, or 1:20-20:1. The 3-alkylthienyl and the unsubstituted thienyl monomeric units are present in a ratio of 1:4-4:1. The 3-alkylthienyl and the unsubstituted thienyl monomeric units are present in a ratio of 1:1, or 0.9:1, or 0.8:1. The 3-alkylthienyl is 3-n-do decylthienyl. A film of the polymer possesses a saturated mobility value and/or a linear mobility value greater than does a comparable film of a polythiophene polymer consisting of monomeric units of 3 -alkylthienyl only. A film of the polymer has a pre-annealing saturated mobility of at least 1 .6E-3 cm2/V-sec under conditions where comparable film of a polythiophene polymer consisting of monomeric units of a 3-alkylthienyl only has a pre-annealing saturated mobility of 2.6E-4 cm2/V-sec. A film of the polymer has a pre-annealing linear mobility of at least 1.0E-3 cm2/V-seconds under conditions where a comparable film of polythiophene polymer consisting of monomeric units of 3-alkylthienyl only has a pre-annealing saturated mobility of 3.1E-4 cm2/V-sec. The photovoltaic system comprises PC70BM, where the fill factor is in excess of 60%. Preferred Method: The method further comprises precipitation of the copolymer with an alcohol, followed by a step of recovery of the solid copolymer, after contacting the mixed organometallic solution and the nickel catalyst, extracting the solid copolymer with an alkane solvent, or extracting the solid copolymer with a halocarbon solvent, or sequentially extracting the solid copolymer with an alkane solvent and a halocarbon solvent, and annealing the film of the copolymer, where annealing comprises heating at 150 degrees C for 30 minutes. The method comprises forming a film of the copolymer. EXAMPLE - 36 mol% 1,2-Bis(diphenylphosphino)ethane nickel(II) chloride (NiDPPE) was weighed into 20 ml scintillation vial. A septum was placed on top of the vial, and it was purged with argon gas. Then, 10 ml tetrahydrofuran (THF) was cannulated into the vial, followed by a slurry of THF/NiDPPE. The two organozincs (100 mole% unsubstituted thienyl, 90 mole% 3-(C12)thienyl) were cannulated into a single bottle and this solution was cannulated into the flask at a very fast drip rate. Once the internal temperature reached 40 degrees C, the mixed organozinc solution was cannulated at a rate to maintain the 40 degrees C internal temperature. The sample was taken out of the reaction. The reaction was stirred for 24 hours from the start of the addition, then was worked up. The reaction mixture was poured into a 500 ml beaker containing 200 ml of methanol and a stir bar and was allowed to stir for 30 minutes. The stirring was then turned off and the solid precipitate was allowed to settle for 1 hour. The solid copolymer was then filtered, placed in a drying dish then placed in a vacuum desiccator for 2 days.