Electrical conduction mechanisms and dielectric properties of thermally evaporatedN-(p-dimethylaminobenzylidene)-p-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 ofN-(p-dimethylaminobenzylidene)-p-nitroaniline (DBN) have been reported. The DC conductivity indicates a thermallyactivated carrier hopping rate; it increases with increasing temperature. The electronicparameters such as activation energy and room temperature conductivity are in the regimeof semiconductors. The obtained experimental results of the AC conductivity have beenanalysed with reference to various theoretical models. The analysis shows that thecorrelated barrier hopping (CBH) model is the appropriate mechanism for the electrontransport in DBN film. Application of the CBH model reveals that the electronicconduction takes place via bipolaron hopping processes in the whole temperature range ofstudy. Both the dielectric constant and the dielectric loss showed a decrease with increasingfrequency while they increased with increasing temperature. The barrier height,WM, between charged defect states was calculated according to the theory of hopping ofcarriers over a potential barrier.