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Abstract
We have applied square wave voltages to smectic liquid crystal cells in order to measure the transient ionic current as a function of field and temperature. The measured ionic current shows a delay peak, which can be explained by ion generation. The precise study of this peak shows that the mechanism involved is electro-absorption at the surface electrodes. We have observed a weak activation enercy E o = 0.68 eV and an exponential dependence on the square root of the field. Since the generation occurs throughout the measurement period, it hides the real dirft current. To describe the ionic transport, a method has been developed to extract the real drift current from the measured ionic current. The results give a Gaussian type transport with a mean mobility μ = 1.7 × 10−7 cm2/V · s at T = 25°C and an activation energy E trap = 0.8–0.9 eV.