Optical Interference Effects by Metal Cathode in Organic Light-Emitting Diodes

The dependence of light intensities of organic light-emitting diodes (OLEDs) on the distance of emission zone to metal cathode is investigated numerically. The investigation is based on the half-space optical model that accounts for optical interference effects of metal cathode. We find that light intensities of OLEDs are functions of the distance of emission zone from the metal cathode because of the effect of interference of the metal cathode. This interference leads to an optimal location of emission zone in OLEDs for the maximum of light intensities. Optimal locations of emission zone are numerically shown in various emitting colour OLEDs with different metal cathodes and these results are expected to give insight into the preparation of high efficiency full colour or white light OLEDs.