Prediction of the current versus voltage behavior of devices based on organic semiconductor guest-host systems

Organic semiconductor blends are commonly used in organic based (opto-) electronic devices. They are composed of two types of (macro-) molecules, referred to as the guest and host. To achieve optimum device operation, the chemical nature, electronic structure, molecular order and the relative concentration of the guests and host are crucial. Here, we present simulation results of the current density versus the voltage (J-V) behavior of a two terminal device based on a variable-range hopping model in which the electronic states of the guest and host are represented by two Gaussian distributions. The J-V behavior is investigated for various energetic mismatches between guest and host states, widths of the distribution as well as the guest concentrations. Finally, a simple tool enabling easy prediction of the J-V behavior of organic host-guest diodes is derived. (C) 2008 Published by Elsevier B.V.