2. Mechanisms involved

Today, our understanding of the phenomena involved in the electroluminescence of organic materials is still incomplete. This is partly due to the fact that, by their molecular nature, organic compounds are more complex than inorganic semiconductors. The models developed for inorganic semiconductors only imperfectly reflect the mechanisms encountered in organics. What's more, the operation of an organic light-emitting diode depends not only on the chemical nature of the material used (small molecule or polymer), but also on the structure of the diode itself (nature of the electrodes, introduction of hole and/or electron injector layers, etc.).

Nevertheless, numerous studies are currently underway to understand the mechanisms of charge injection, transport and recombination in organic EL diodes. In the following, we will review the main results. For a fuller description,...