C–H σ-Dopants Mediated n-Doping of Conjugated Polymers: Mutual Designs and Multiscale Characteristics

Conjugated polymers have gained significant interest in recent decades, offering complementary advantages over traditional inorganic electronic materials in ways such as solution processability, mechanical flexibility, and structural diversity afforded via bottom-up organic synthesis. Doping is a crucial aspect for advancing these materials as it adjusts the energies, spatial distributions, and occupancies of the orbitals, affecting the carrier density and mobility. Compared to their p-doping counterparts, n-doping strategies lag behind in their performances. The combination of p-type and n-type polymers is essential for many organic optoelectronic applications, which signified the importance of developing novel n-doping solutions. Traditional electron transfer-type n-dopants, which rely on a low ionization potential for their reactivity, face challenges in processability, reversibility, and sensitivity to ambient conditions. In contrast, C–H σ-dopants operate through different mechanisms. This could open up new avenues to reconcile these conflicts.