Admittance spectroscopy of organic light emitting diodes

Abstract

Admittance or impedance spectroscopy is one of the powerful tools to study the equivalent circuit model and the relaxation and loss processes in organic and inorganic materials and devices. The frequency dependent properties of small molecules based single and double layer organic light emitting diodes have been studied. The single layer diodes can be modeled as a simple parallel resistor-capacitor circuit. In the double layer structure device, the frequency dependent properties are similar to those of the emitting layer. This is maybe related with the space charge, which is believed to be formed in the emitting layer. The equivalent circuit models of the single and double layer structures are presented.