As a family member of polythiophenes, PBT1 (also known as PBDD4T) has a backbone consisting of repeating benzodithiophene-4,8-dione and α-quaterthiophene units. π electrons can be delocalized effectively through the alternative electron push?pull effect, resulting a low band-gap polymer. Also, with four ethylhexyl branched side chains, the polymer is more soluble in most of organic solvents.
