Influence of electro-active organic materials physical structure on their electrical activities

The physical structure and stability of the columnar liquid crystal have been explored by DSC in the bulk state. Thermally stimulated currents and dynamic dielectric spectroscopy experiments have been adapted to sample thickness (15±3 μm). Dielectric spectra show the manifestation of the glass transition and the melting transition; we can also distinguish the dielectric manifestation of the liquid crystal-crystal transition. These results are coherent with DSC thermogram. Then we have shown in fluorinated ferroelectric polymer the dipolar contribution in the crystalline phase is not sufficient to explain the dependence of the pyroelectric activity on temperature. We have also studied the physical structure evolution during storage or annealing above the glass transition and their influence on pyroelectric properties.