Drift-diffusion simulations of thermally activated delayed fluorescence OLEDs

In this work we present drift-diffusion simulations of a blue-emitting thermally activated delayed fluorescence (TADF) OLED. We exploited the ability of the multi-particle drift-diffusion model to explicitly calculate the charge transport for the different sub-populations in the TADF emitter, including singlet and triplet exciton states. The inclusion of proper models for the band-to-band transitions, for bimolecular recombination mechanisms and for inter-system crossing allows to investigate the device operation under different conditions. Moreover, it provides insight into the role of triplet-triplet annihilation and triplet-polaron quenching for the roll-off in internal quantum efficiency, which typically occurs in TADF OLEDs.