Two-Step Design Rule for Simultaneously High Conductivity and Seebeck Coefficient in Conjugated Polymer-Based Thermoelectrics.

The trade-off between enhancing conductivity (σ) through doping while concurrently observing a reduction in the Seebeck coefficient (S) presents a key challenge in organic thermoelectrics. Here, a two-step structural design strategy is developed, where the first step enhances the backbone planarity which enhances the conductivity by an improved ordering of conjugated polymers (CPs). The second step, which is fluorination of the backbone, improves the Seebeck coefficient by the controlled induction of energetic disorder, stemming from the fluorine's disruption of the homogeneous electrostatic potential across the CP backbone.