Determination of capacitance-voltage characteristics of organic semiconductor devices by combined current-voltage and voltage decay measurements

We present in this paper a new method, based on measurements of conventional direct current-voltage (I-V) characteristics and transient voltage-time (V-t) characteristics during the discharge process, for determining capacitance-voltage (C-V) characteristics of organic semiconductor devices. Derivatives of I-V and V-t, dI/dV and dV/dt, are related with C by a simple formula \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ C = - V \cdot \frac{{dI/dV}} {{dV/dt}} $$\end{document}. The validity of the method is confirmed by experimental data measured from a set of single-organic-layer devices with different layer thicknesses.