Space-charge limited conduction in polyaniline films

Polyaniline emeraldine base (PANI-EB) powder was synthesized by oxidative polymerization of aniline. The PANI-EB films were prepared by the solution-casting technique. The temperature-dependent de conductivity measured in the range 173-303 K suggests that the PANI-EB is a quasi-one-dimensional disordered conductor. The current-voltage characteristics of the PANI-EB films measured in the range 333-383 K showed the SCLC mechanism. The SCLC parameters such as free carrier density (p₀), trap density (p_t,), the ratio between free carrier density to the total carrier density (θ), mobility (μ) and the effective hole mobility (μ_eff) were calculated. The activation energy (E_a = 0.32 eV) and the Fermi level (E_F = 0.42 eV) were estimated. As well as these, the trap parameters such as the trap filled limit voltage (V_TFL), the shallow trap density (N_t,), the depth of the dominant trap level (E_t - E_v), the density of states within the hole mobility edge (N_v) and the characteristic energy (E_c) were also calculated and presented. The exponential type of traps distribution with large number of traps was found to be due to the disorder and moisture in the polymer films.