Injection and charge transport processes of polymer light emitting diodes

The development of multilayer light-emitting diodes (LED) consisting of evaporated organic materials by Tang and van Slyke [1] stimulated significant progress in the development of design concepts of multilayer structures as well as in molecular design of fluorescent dyes and charge transport dyes. Since the first discovery of polymer-based light emitting diodes in 1990 [2] the interest of the charge transport phenomena in such devices increased rapidly. The efficiency of the injection of electrons and holes plays an important role for the electroluminescence of LED's. The electronic nature of the organic materials determined the parameters for good electron and hole injection and transport capability.