P2: Degradation Mechanisms in Organic Electronics

The aim of this project is to develop scale-bridging simulation methods to understand the chemical mechanisms of degradation in the guest-host materials.

In phosphorescent OLEDs, excitons are transferred to the phosphorescent emitter com-pounds which emit light. Experimental results indicate that due to exciton-polaron combination in the emitter host material the emitting properties are lost irreversibly, resulting in reduced device lifetimes and thus unsolved problems in this technology.

In order to model the degradation process starting with exciton creation, in project P2 methods for different scales are combined. Molecular dynamics (MD) and kinetic Monte Carlo (kMC) are used to model the structures in the target materials. Ab-initio quantum chemistry is employed to compute the creation of (triplet) exciton creation and coupling matrix elements required to describe (triplet) exciton transport. Charge and exciton transport are treated using (long range corrected) density functional tight binding (LC-DFTB). Finally, the actual degradation of the material is investigated using (ab-initio) excited-state quantum chemistry.