Bias and Temperature Effect on the Carrier Transport Parameters in Impedance Spectroscopy

摘要

We simulated the negative capacitance-frequency curves for the organic semiconductor Alq_3 using the Drude model equation to assess the applicability of the "universality of photocurrent transients". Using the data reported by Berleb et al, shape invariance was observed in these curves after normalization with respect to frequency and taking into account the bias dependence. Our results suggested that the reported frequency shifts in Berleb's measurements were primarily related to changes in the complex carrier mobility at the different biases. Normalization of the capacitance-frequency curves at different temperatures also showed shape invariance when normalized. The observed changes in the carrier mobility as a function of temperature were essentially the same as what one would expect from a disordered solid with Gaussian density of states. Our model therefore provided an alternative venue to determine the "universality of photocurrent transients" with focus on the complex carrier mobility.