Electric and optical properties of some new functional lower-rim-substituted calixarene derivatives in thin films

Electric (d.c. conduction mechanism, the influence of environmental humidity, thermistor effect) and optical properties of new five substituted calixarene derivatives in thin films have been studied. The films behave as typical n-type polycrystalline semiconductors with activation energy of the electric conduction between 0.26 and 2.36 eV. In the higher temperature range, the electron transport was explained in the frame of the band gap representation model, while at lower temperatures, the Mott’s variable-range hopping conduction model was found as appropriate. In terms of electric conductivity, these compounds are practically insensitive to ambient humidity below 53% RH, their sensitivity increasing greatly with the humidity in the range of 53–98% RH. Study of optical absorption spectra in the photon energy range of 0.71–4.03 eV (UV–Vis–NIR) revealed direct optical band gaps between 2.64 and 3.83 eV. Actual compounds show promising potential for thermistor applications.