Fig. 1

Chemical structures of (a) thiophene-TzTz-thiophene and (b) thiophene-BBTz-thiophene building units with alkyl, alkoxy, and ester groups, and (c) BBTz-based polymers, PDBTz1 and PDBTz2

Chemical structures of (a) thiophene-TzTz-thiophene and (b) thiophene-BBTz-thiophene building units with alkyl, alkoxy, and ester groups, and (c) BBTz-based polymers, PDBTz1 and PDBTz2