ELECTRICAL AND OPTICAL-PROPERTIES OF SUBLIMED FILMS OF HEAVY-FRACTION RARE-EARTH-ELEMENT BISPHTHALOCYANINES

Steady-state electrical measurements and optical-absorption experiments were performed on 50 nm thick samples of sublimed heavy-fraction rare-earth-element bisphthalocyanines films. From the Arrhenius plot of ln sigma(T) (where sigma(T) is the conductivity at temperature T it was found that two conduction regimes existed. The activation energy of 0.18 eV at high temperatures (T> 162 K) relates to the distance of singlet states below the conduction band. The low-temperature activation energy of 4 meV indicates hopping conduction between localized states close to the Fermi level. Visible optical spectra in both absorption and transmission modes were obtained for the sample. The absorption data were analysed in terms of a well-known power law, and a value of 2.3 eV was found for the optical gap, E0. Estimates of the refractive indices and the dielectric constants were made over the visible spectrum.