Study On The Model Of Organic Electroluminescence Devices

In recent years, the study of organic solid electric devices has attracted much interest and obtained great achievements. At present, the devices with good stability, long lifetime, low applied voltage is required. In order to improve the performances of organic light-emitting devices (OLEDs), the mechanism running in electroluminescence processes has been studied deeply. But it's not very clear until now for the complexities in its mathematical treating and experimental result analysis, and because the carrier transport in organic semiconductors is different from in inorganic semiconductors, it is greatly needed to build a theoretical model holding for organic semiconductors. Therefore, we have done following works.1. For single layer organic film devices, with ohmic injection, the analytical relationship between current density and applied voltage has been derived for trap free organic film. The relationship between current and film thickness, the relationship between current and relative trap depth have been studied by using numerical method. At same time, the distribution of electric potential, electric field, carrier density in the bulk of organic film have been numerically simulated when with traps in organic film.2. The carrier injection models at the interface between electrode and organic film are reviewed, and a new theoretical model is developed to explain the hole inject from ITO anode into organic semiconductor G1-para-Ir(ppy)₃.3. The performance of OLEDs is closely related to the electric field and carrier density distribution in the organic layer. Based on the drift-diffusion theory for the motion of charge carriers, we adopted the method of numerical calculation to study the potential, electric field, carrier density and recombination rate in the organic material.4. Based on the Miller-Abrahams formalism for hopping conduction, an analytical model for charge transport at OO interfaces of bilayer device with one carrier has been developed by considering the differences between OO interfaces and metal-organic interfaces. This model can be used to self-consistent calculations of the current density, field distribution and other characteristics in multiplayer organic semiconductor devices. The dependence of current, field and carrier distribution on temperature are numerically analyzed under organic-organic interface limited (OOIL) current conduction. Describe an analytical model of bilayer device with two carrier. The relationship between current and voltage, the distribution of electrons, holes, electric field and recombination rate have been studied by using numerical method.