d.c. electric conduction mechanism of some newly synthesized indolizine derivatives in thin films

Temperature-dependent d.c. electric conductivity of some recently synthesized indolizine derivatives is studied. Thin-film samples (d = 0.10–0.30 μm) spin-coated from chloroform solutions onto glass substrates were used. Organic films with reproducible electric properties can be obtained by submitting as-prepared samples to a heat treatment within temperature range of 301–493 K. The studied polycrystalline compounds show typical n-type semiconductor behavior. The activation energy of the electric conduction ranges between 0.32 and 1.07 eV. Some correlations between semiconducting characteristics and molecular structure of the organic compounds have been discussed. In the higher temperature range (T > 415 K), the electron transport in present compounds can be interpreted in terms of the band gap representation model, while in the lower temperature range (T < 339 K), the Mott’s variable-range hopping conduction model was found to be suitable.