Charge Transport Properties of PBFDO at Various Doping Levels: An Electrochemical Control and Hall Effect...

N-type polymer poly(benzodifurandione) (PBFDO) has demonstrated record-high conductivity in its highly doped state; however, various applications require optimized rather than maximized doping levels. Herein, we systematically investigate the relationship between doping level and charge transport properties in PBFDO using electrochemical dedoping to precisely control doping states, coupled with Hall effect measurements to directly characterize the carrier concentration and mobility. During the dedoping process, both carrier concentration and mobility simultaneously decrease from 2.03E22 to 7.85E21 cm^-3 and from 0.40 to 0.16 cm² V^-1 s^-1, respectively, with conductivity reducing from 1286 to 206 S cm^-1. Spectroelectrochemical analysis reveals characteristic absorption changes during dedoping, while EPR analysis revealed a transition from polaron pairs to single polarons during dedoping. GIWAXS further demonstrated that dedoping led to an increased interlayer spacing and structural disorder, consistent with a reduced mobility. Unlike conventional conjugated polymers, PBFDO's unique behavior derives from its unique in situ n-doping process and the incorporation of protons acting as counter cations. This study provides critical insights for tailoring PBFDO's electronic properties across different doping regimes for diverse applications.