The energy and spin parameters of 3-alkylthiophene oligomers and their composites with aromatic hydrocarbons have been calculated. The coexistence of polarons with different degrees of delocalization in the studied compounds has been identified. It has been revealed that the electronic and spin properties of the composites undergo a periodic change initiated by the interaction of the oligomers with aromatic nanoadditives. The anisotropic parameters of spin Hamiltonians have been obtained for the systems under study, and their high-resolution EPR spectra have been calculated.