AC conductivity and dielectric relaxation of bulk tris (8-hydroxyquinoline) aluminum organic semiconductor

Abstract

The frequency dependent conductivity and dielectric behavior of bulk tris (8-hydroxyquinoline) aluminium(III) (Alq3) have been studied in the temperature range (293–473 K) and frequency range (102–5 MHz). The AC conductivity, σac, was found to be proportional to ωs (where ω is the angular frequency). The exponent frequencies was found to be less than unity and decreased by increasing temperature. This behavior suggests that the correlated barrier hopping (CBH) model is the most predominated conduction mechanism. Both the dielectric constant ε1 (ω) and dielectric loss ε2 (ω) are decreased with the increase of frequency while they are increased with the increase of temperature in the investigated ranges. The complex diagram of electric modulus gives an evidence of existence of the type of Debye relaxation. The relaxation time (τ) and activation energy for relaxation (Ea) were determined.