Abstract
Temperature-dependent d.c. electric conductivity of some recently synthesized organic compounds, 4,7-phenanthroline
derivatives is studied. Thin-film samples (d=0.34-0.63 m) spin-coated from dimethylformamide solutions onto glass substrates
have been used. Organic films with reproducible electron transport properties can be obtained if, after deposition, they are
submitted to a heat treatment within temperature range of 298523K. Examined organic compounds in thin films are
polycrystalline and display typical n-type semiconductor behavior. The activation energy of d. c. electric conduction ranges
between 0.09 and 0.46 eV and is influenced by nature of substituents, degree of conjugation systems and packing capacity of
compounds. In the higher temperature range (T>433 K), the electron transport in examined compounds can be interpreted in
terms of the band gap representation model, while in the lower temperature range, the Mott’s variable-range hopping conduction
model was found to be appropriate. Some of the investigated compounds hold promise for thermistor applications.