At the insulator state, moderately doped EB exhibits the lossy dielectric characteristics with significantly lower DC conductivity due to strong localization. The mid-IR optical properties of PANI-EB features the strong absorption from infrared active vibrational (IRAV) modes caused by bound polarons . As an absorption caused by correlated interaction between charge carriers and structural distortion, IRAV peaks in CPs are known to be dependent on the ability of delocalization associated with different backbones, side chain species, and doping levels .