method further comprises the steps of chain extension to form abc block copolymer preferably the first thiophene monomer the second thiophene monomer or both are substituted in the 3 position the 4 position or both preferably the polymerizing is carried out with a initial monomer initiator molar ratio of about 140 1 or less preferably the polymerizing is carried out with an initial monomer initiator molar ratio of about 80 1 or less preferably the polymerizing is carried out at about 0 u00b0 c to about 50 u00b0 c and wherein the ab block copolymer is a regioregular polythiophene block copolymer preferably the ab block copolymer is a regioregular polythiophene block copolymer another embodiment is a composition comprising an ab block copolymer wherein the a block is a regioregular polythiophene and the b block is also a regioregular polythiophene the regioregular polythiophene can be for example at least 90 regioregular or at least 95 regioregular or at least 98 regioregular preferably the a block and or the b block regioregular polythiophene is substituted at the 3 position at the 4 position or both preferably the a block and or the b block regioregular polythiophene is substituted at the 3 position preferably the a block and or the b block regioregular polythiophene is substituted at the 4 position preferably the a block and or the b block regioregular polythiophene is substituted at the 3 position and.