Anisotropy of Optical functions of conjugated polymer thin films by spectroscopic ellipsometry

Optical properties of thin films of conjugated poly~arylenephenylene! polymers have been
determined using variable angle spectroscopic ellipsometry. Dispersion of the complex refractive
index parallel, Ni5(ni1iki), and perpendicular, N'5(n'1ik'), to the film plane are reported for
the photon energy range 1.5–5.0 eV. The energy dispersion in the optical properties has been
analyzed using a three-phase model and Lorentzian dispersion functions for the polymers. The
resonant frequencies of the Lorentzian oscillators describe the fundamental p- p* optical transition
polarized parallel to the polymer chain and indicate additional optical transitions polarized
perpendicular to the polymer chain that are introduced by interchain interactions. Dependence of the
optical anisotropy and fundamental p- p* optical transition on the polymer backbone is discussed.
© 2003 American Institute of Physics. @DOI: 10.1063/1.1610236#