Side-chain engineering of self-doped conjugated polyelectrolytes for organic electrochemical transistors

A series of conjugated polyelectrolytes (CPEs) containing cyclopentadithiophene-alt-benzothiadiazole were synthesized. Their alkyl chain length was varied from 2–5 carbons in order to investigate the effects on their optical, electrochemical and morphological properties. CPEs are mixed conductors and can be used as the active layer in accumulation mode organic electrochemical transistors (OECTs). Their transconductance, volumetric capacitance, and ionic and electronic conductivity are dependent on their alkyl chain length. DFT calculations help explain the differences in the ease of doping as a function of molecular structure.