TECHNOLOGY FOCUS - POLYMERS - Preferred Process: In the method (P1) the product of the reaction is a regioregular polythiophene. Preparation of thiophene-based polymer (P2) involves providing at least one asymmetrical organic dihalogen polymerization monomer adapted for metal-assisted cross coupling polymerization, where the monomer comprises at least one thiophene ring which is substituted with an aryl group, and two halogen groups; where halogens are different and are selected from chlorine (Cl), bromine (Br), or iodine (I); and polymerizing the monomer. The polymerizing step of process (P2) involves reacting the monomer (preferably monomer (I)) with an organomagnesium reagent, or organomagnesium reagent comprising an organomagnesium component and a metal activation agent to form an intermediate; and reacting the intermediate with at least one metal complex. In the process (P2) the monomer is an asymmetrical monomer of formulae (I), (II), (III), (IV), (V) and (VI). Preparation of (P3) poly(3-arylsubstituted) thiophene involves providing at least one thiophene monomer (I); and polymerizing the monomer. The process (P3) involves dissolving the monomer (I) in at least one solvent to form a mixture; adding the organomagnesium reagent to the mixture; adding an initiator to the mixture; and recovering a poly(3-arylsubstituted thiophene). The polymerizing is carried out under living conditions. The polymerizing step of process (P3) is carried out to produce a homopolymer, copolymer, or block copolymer. The polymerizing step of process (P3) is carried out in the presence of a polymer, thiophene-based polymer, thiophene-based polymer comprising alkyl, alkoxy, aryl, or combination of their side groups, or poly(3-alkylthiophene) polymer to form a block copolymer of formula (VII).X1=I or Br, (preferably I);X'=Br, or Cl (preferably Br);andAr=aryl (optionally substituted by at least one alkyl, alkenyl, alkynyl, or alkoxyl (all optionally substituted), or phenyl (optionally substituted by branched alkyl) (preferably 4-octylphenyl or 4-(2-ethylhexyl)phenyl;R'=substituent adapted to allow for polymerization of the monomer;Y'=S, O, Se;n and m=1-500 (preferably 1-300);andA'=1-20C alky.Preferred Components: In the process (P1) the unsaturated ring compound is a heterocyclic ring compound selected from thiophene compound, pyrrole compound, fluorene compound, or phenyl compound; and the unsaturated ring compound comprises alkyl, aryl, or alkoxy ring substituent. The unsaturated ring compound is a thiophene compound substituted at the 2-position with bromo, at the 5-position with iodo group and at 3-position with alkyl, alkoxy, or aryl substituent. The metal activation agent comprises lithium, magnesium, potassium, or zinc (preferably lithium). In the process (P2) the monomer comprises at least two rings, where at least one of the rings is a thiophene; at least two thiophene rings; at least two fused thiophene rings; or bithiophene containing two directly linked thiophene rings further linked by a spacer atom. Preferred Composition: In the composition (C1) the first halogen is bromine; the second halogen is iodine; and the aryl group further comprises at least one optionally branched alkyl group bonded to the aryl group. EXAMPLE - 2-Bromo-3-(4-(2-ethylhexyl)phenyl)-5-iodothiophene (0.67 g) and anhydrous tetrahydrofuran (THF) (5 ml) were mixed. Then a solution of iso-propylmagnesium chloride:lithium chloride (1 M, 1.3 ml) in THF was added and stirred at ambient temperature to give the reaction mixture (R1). 2-Bromo-3-hexyl-5-iodothiophene (0.26 g), dodecane (0.1 ml), and anhydrous THF (23 ml) were mixed. Then a solution of iso-propylmagnesium chloride (2 M, 0.34 ml) in THF was added and stirred at ambient temperature for 10 minutes to obtain reaction mixture (R2). After this a suspension of bis(diphenylphosphinol)propane)nickel(II)chloride (Ni(dppp)Cl2) (5.2 mg) in THF (0.01 M) was added and reaction mixture (R2) was heated to 35 degrees C and stirred for 45 minutes. After this the reaction mixture (R1) was added and heated to 55 degrees C and stirred for 16 hours. Then hydrochloric acid (5 N) was added and the reaction mixture was precipitated into methanol. After workup block-copolymer, poly(3-hexylthiophene)-b-poly(3- (4-(2-ethylhexyl)-phenyl)thiophene) (P3HT-PPEHPT) (50%) was obtained as a dark purple solid with number average molecular weight of 34800.