Balancing Solubility and Thermoelectric Performance in π-Extended Poly(benzimidazoanthradiisoquinolinedione) Ladder-Type Conjugated Polymer

Herein, we report a new n-type ladder-type conjugated polymer, dichlorinated poly(benzimidazoanthradiisoquinolinedione) (Cl2–BAL), that possesses a slightly twisted polymer backbone and a preferred edge-on orientation. Upon n-doping, its maximum electrical conductivity and power factor in thermoelectric devices reached 1.1 ± 0.07 S cm–1 and 3.52 ± 0.37 μW m–1 K–2, respectively, and is almost on par with the best performing ladder-type conjugated polymer BBL. As compared to our previously reported tetrachlorinated analogue Cl4–BAL, our results demonstrate that the chlorine atoms can influence not only the torsion angle but also the orientation and π–π stacking, which in turn dramatically affects its performance.