Optical Anisotropy and Orientation Order of Uniaxial Films of Conjugated Polymers

Abstract
The uniaxial film of conjugated polymer with macromolecules as a set of subunits of different lengths was studied. For this film, the connection between the components ε_(1,2)j(ω) of the dielectric function ε_j(ω) = ε_1j(ω) + iε_2j(ω) and the orientation order parameter σ was established. The orientation order parameter σ of the dipole moments of molecular transitions corresponds to an isolated absorption band of light with polarization along (j = ||) and across (j = ⊥) the optical axis of the film. New methods have been implemented for determining σ of the P3OT polymer film. The P3OT polymer film is characterized by a planar orientation of subunits and known dependences ε_(1,2)j(ω) in the regions of transparency and low-frequency electron absorption. The anisotropy of the components f_j(ω) = 1 + L_j[ε_j(ω) – 1] of the local-field tensor was taken into account. The experimental values of the components L_j of the Lorentz tensor for the P3OT film were determined using the dependences ε_1j(ω) in the visible transparency region. The combined effect of the length and orientation order of the subunits, as well as dynamic dipole-dipole interactions between subunits (local-field effects) on the position of the maxima of the ε_2j(ω) bands was shown.

Keywords: conjugated polymers, P3OT, anisotropic polymer films, orientation order, local-field effects