Numerical Study Of Charge Transport In Organic Light-emitting Devices

The ease of fabrication, high efficiency, low cost and excellent compatibility with flexible and curved substrates make organic light emitting devices appealing candidate for display and illumination applications. Although it has been about thirty years since the first organic light emitting device was invented, the device physics of organic light emitting devices needs to be further studied. Charge transport mechanism is one of the key physical processes in organic light emitting devices. Based on the above reasons, following works have been done:1. In order to obtain electron mobility and hole mobility of the NdPc2films, the single-electron devices and the single-hole devices were fabricated, and the current-voltage characteristics of the devices were studied. The effect of different cathode materials on the performance of organic semiconductor devices was numerically studied by using the space charge limited current model in the absence of traps. The hole mobility and electron mobility of NdPc2films were obtained by fitting analysis.2. The distinctions of the doping in the emitting layer and the doping in the transport layer were analyzed. The effects of the dye doping and the level trap doping on the performance of organic light emitting devices were discussed. The theoretical model of the doping single energy trap in emitting layer of single layer organic light-emitting devices was built, and the effects of doping in emitting layer of the following different devices on the spatial distribution of the free electron concentration, the free hole concentration, the recombination rate density and the electric field were numerically studied:(1) The single layer organic light emitting devices had ideal bipolar emission layer and formed good ohmic contact with electrode, and the same trap concentration or trap depth electron traps and hole traps were doped into the emitting layer simultaneously;(2) The single layer organic light emitting devices had ideal bipolar emission layer and formed typical schottky contact with electrode, and the electron traps with a certain trap concentration or trap depth were doped into the emitting layer;(3) The single layer organic light emitting devices had the unipolar emission layer and formed typical schottky contact with electrode, and the electron traps with a certain trap concentration or trap depth were into the emitting layer. 3. The numerical model of the doping single energy trap in emitting layer of bilayer organic light-emitting devices has been built. And the effects of doping single energy electron traps in emitting layer on the distribution of the free electron concentration, the free hole concentration, the recombination rate density and the electric field were studied numerically under the condition of electrons’ and holes’ schottky injection.