Engineering Carrier-Dopant Interactions to Improve Charge Transport Properties in Highly-Doped Semiconducting Polymers

Doping is a powerful technique that can easily tune the electrical properties of semiconducting polymers and hence, grant flexibility to their applications. Highly-doped semiconducting polymers with high electrical conductivity have found extensive use in thermoelectric materials and bioelectronics. However, the low dielectric constant of semiconducting polymers causes strong Coulomb interactions between carriers and dopants. As a result, carriers cannot be effectively transported through the host polymer network and tend to localize within a few monomer units or π-stacks. These limitations, distinct from those observed in conventionally doped inorganic semiconductors, necessitate novel engineering strategies to not only generate more charge carriers but also reduce unfavorable electrostatic interactions between carriers and dopants in doped semiconducting polymers. This talk will explore straightforward engineering methods to reduce Coulomb interactions between carriers and dopants in highly-doped semiconducting polymers. The corresponding reduction in charge localization and improved transport achieved through these methods will be discussed. Additionally, I will explore the effects of molecular structures that exhibit resilience to the energetic disorder caused by electrostatic carrier-dopant interactions on charge transport properties. Lastly, the talk will introduce the significant thermoelectric performance achieved in our research and discuss the potential of thermoelectric materials based on doped semiconducting polymers for the near future.