Electrical conduction mechanisms and dielectric properties of thermally evaporated<i>N</i>-(<i>p</i>-dimethylaminobenzylidene)-<i>p</i>-nitroaniline thin films

Abstract

The electrical conductivity (DC, AC) and dielectric properties' dependence on temperature (293–393 K) and on frequency (0.1 Hz–100 kHz) of thermally deposited thin films of N-(p-dimethylaminobenzylidene)-p-nitroaniline (DBN) have been reported. The DC conductivity indicates a thermally activated carrier hopping rate; it increases with increasing temperature. The electronic parameters such as activation energy and room temperature conductivity are in the regime of semiconductors. The obtained experimental results of the AC conductivity have been analysed with reference to various theoretical models. The analysis shows that the correlated barrier hopping (CBH) model is the appropriate mechanism for the electron transport in DBN film. Application of the CBH model reveals that the electronic conduction takes place via bipolaron hopping processes in the whole temperature range of study. Both the dielectric constant and the dielectric loss showed a decrease with increasing frequency while they increased with increasing temperature. The barrier height, WM, between charged defect states was calculated according to the theory of hopping of carriers over a potential barrier.