Enhanced N- and P-Doping of Polymers Through Electrochemical Copolymerization of 1-(Perfluorophenyl)-2-(Thiophen-3-ylmethylene) Hydrazine and Bithiophene

The urgent demand for advanced energy storage systems (ESSs) has intensified the exploration of conductive polymers (CPs) due to their lightweight nature, design flexibility, and dual p -/ n -doping capabilities. However, achieving stable n -type doping in π -conjugated systems remains a major challenge, and a rational molecular design is necessary. In this work, we report the synthesis of an electrochemical copolymer based on bithiophene (BT) and 1-(perfluorophenyl)-2-(thiophen-3-ylmethylene)hydrazine (FTh1) monomer, containing a strong electron-withdrawing fluorinated substituent. While FTh1 monomer electropolymerization fails under our experimental conditions, its copolymerization with BT enables the formation of stable, adherent films on glassy carbon electrodes. These films reveal a reversible and stable n -doping response attributed to copolymer species, which is absent in pristine polybithiophene, showing a successful stabilization of carbanionic species. Additionally, incorporation of FTh1 monomer induces significant shifts in p -doping profile and enables charge trapping during redox cycling. Furthermore, scan rate-dependent analyses demonstrate diffusion-controlled ion transport for both anodic and cathodic processes. These findings highlight the potential of strategic monomer design to modulate the redox behavior of CPs, paving the way for their application in next-generation symmetric pseudocapacitors.