Unraveling exciton processes in Ir(ppy)₃:CBP OLED films upon photoexcitation

Emissive layers in phosphorescent organic light-emitting diodes commonly make use of guest–host blends such as Ir(ppy)3:CBP to achieve high external quantum efficiencies. However, while the blend has been studied experimentally, crucial questions remain regarding how exciton diffusion is dependent on distribution guest host, which can currently only be addressed at atomic level via computational modeling. In this work, kinetic Monte Carlo simulations are utilized gain insight into films. The effects both concentration and density various system properties analyzed, including probability singlet excitons being converted triplets, those triplets decaying radiatively. Significantly, these suggest that triplet occurs almost exclusively guest–guest Dexter transfer quenching induced by intermolecular dipole-dipole interactions a negligible effect densities due prevalence triplet–triplet annihilation. Furthermore, results for vacuum deposited morphologies derived from molecular dynamics compared obtained using simple cubic lattice approximation with randomly distributed molecules. We show differences host-based processes observed, overall, fate good agreement two morphology types, particularly guest-based low concentrations where clustering limited.