Doping-Controlled Magnetization in 1D and 2D Organic Semiconductors

Magnetic materials play a central role in modern technologies such as magnetic data storage, spin-based electronics, and biomedical imaging, where parameters like saturation magnetization and coercivity are crucial performance indicators. Although inorganic ferromagnets and superparamagnets dominate current applications, metal-free organic semiconductors particularly one-dimensional (1D) conjugated polymers and two-dimensional (2D) covalent frameworks have attracted increasing attention due to their tunable intrinsic magnetism. Chemical doping in these systems enables modulation of their electronic band structures and spin-spin interactions. Previous studies on doped conjugated polymers such as polyaniline and P3HT have shown that the nature of the dopant and its spatial configuration strongly influence magnetic behavior however, a thorough theoretical investigation into the factors governing magnetization in doped organic semiconductors has not yet been made.

   In our study, doped organic semiconductors are analyzed using a modified Hubbard model incorporating Ising-type exchange terms to account for charge transport and spin correlation effects. For 1D polymer chains and 2D frameworks, our theoretical analysis demonstrates that magnetization is highly sensitive to dopant geometry, exhibiting saturation behavior at larger dopant separations. The interplay between dopant spacing and concentration is quantitatively assessed to identify optimal doping conditions for enhanced magnetic response.

   Our findings provide molecular-level insight into the mechanisms governing doping efficiency and magnetic coupling, offering guidelines for the rational design of dopant architectures and host-dopant interactions. By linking theoretical predictions with experimental techniques such as electrically detected magnetic resonance (EDMR) and electron paramagnetic resonance (EPR), our work advances the understanding of metal-free organic magnets for spintronic and flexible electronic applications, complementing recent progress in intrinsic organic magnetism.