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 ΔE_σ 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: σ_ac(ω)=A(T). ω^s(T), where s<1. The obtained results have been discussed in terms of the correlated barrier hopping (CBH) model. The density of localized states N_F(E) at the Fermi level and the binding energy W_m were calculated. The dielectric constant ε₁(ω) and dielectric loss 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 W_M 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.