Organic light-emitting diodes

An organic light-emitting diode consists of a thin organic layer sandwiched between electrodes that are capable of injecting a high concentration of electrons and holes when the diode is addressed by an electric field. Electroluminescence results from their bimolecular recombination and the concomitant formation of a fluorescent singlet state of a chromophore. High emission intensity requires efficient injection, the elimination of charge carrier discharge at the counterelectrodes and a high photoluminescence yield of the emitter. Of crucial importance is the choice of electrode materials and organic components based upon their workfunction and their oxidation/reduction potentials, respectively, in conjunction with the structure of the layer assembly. Corrosion effects involving H2O and O-2 can limit the device's performance severely.