A method of reacting bis(R1) 5,5′″-dibromo-3″,4′-difluoro-[2,2′:5′,2″:5″,2′″-quaterthiophene]-3,3′″-dicarboxylate and bis(R2) 5,5′″-dibromo-3″,4′-difluoro-[2,2′:5′,2″:5″,2′″-quaterthiophene]-3,3′″-dicarboxylate to form the polymer: In this polymer R1, R2, R3, R4, R5 and R6 are independently selected from the group consisting of: a halogen, a substituted alkyl, an unsubstituted alkyl, a substituted aryl, an unsubstituted aryl, a substituted heteroaryl and an unsubstituted heteroaryl.