Electrical conductivity and dielectric relaxation behavior of fluorescein sodium salt (FSS)

The ac and dc electrical conductivities and dielectric properties of the fluorescein sodium salt (FSS) have been investigated. The direct current (dc) conductivity shows that the compound is a typical organic semiconductor, as its electrical conductivity increases with increasing temperature. The dc electrical activation energy ΔEσ and the room temperature electrical conductivity equal 0.35 eV and 1.26×10−9(Ωcm)−1, respectively. The alternating current (ac) conductivity of the investigated compound obeys the power law : σac(ω)=A(T).ωs(T)σac(ω)=A(T).ωs(T), where s<1s<1. The obtained results have been discussed in terms of the correlated barrier hopping (CBH) model. The density of localized states NF(E)NF(E) at the Fermi level and the binding energy WmWm were calculated. The dielectric constant ε1(ω)ε1(ω) and dielectric loss ε2(ω)ε2(ω) have been found to decrease with increasing frequency and to increase with increasing temperature over the studied ranges. The value of the maximum barrier height WMWM obtained from Austin and Guintini equations agree with each other. The correlation between the ac conduction and the dielectric properties in organic FSS were verified.