Electronic structure calculations of doped organic materials for electroluminescent devices

Abstract

Recent very promising fabrication advances in organic light emitting diodes have brought out the need for a microscopic understanding of the interaction of light emitters, hole blockers, hole transporters, dopants, and their electroluminescence. We report exploratory quantum calculations on spectra with and without the presence of an external electric field, with different "guest-host" arrangements of emitter and dopant molecules. These calculations, when suitably extended, could be used for predictive optimization of candidate materials, and for the design of optimal layer-structure and layer-ordering etc., in diodes and other proposed structures. The molecules studied are: Scandium 8-hydroxyquinoline as the light emitter, a 1,2,4-triazole molecule as a typical hole blocker, and triphenyl diamine derivatives as hole transporters. The dopant or "guest" molecule was selected to be Nile Red. Studies on the use of a highly conjugated system such as C60 as an element of layer structure are also presented here. The results give an insight into the physical processes at the molecular level and provide guidance in designing optimized material for use in "organic" light emitting diodes. © 1997 American Institute of Physics.