Numerical impedance analysis for organic semiconductors with exponential distribution of localized states

We present a comprehensive numerical impedance spectroscopy analysis of an organic semiconductor device. A physical model that considers localized states is combined with a space- and frequency-resolved numerical framework. We study the details of the frequency-dependent capacitance of an electron-only device and distinguish different trapping regimes depending on the parameters. Depending on the choice of the trapping parameters, a capacitance rise at low frequency is observed. The extraction of the characteristic temperature of the exponential of the trap density of states (DOS) by a simplified method by T. Okachi et al. [Appl. Phys. Lett. 94, 043301(2009)] is investigated. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3633109]