Singlet-triplet quenching in high intensity fluorescent organic light emitting diodes

► Doped fluorescent OLEDs exhibit significant intensity overshoot at the beginning of a current pulse when driven at very high brightnesses. ► The effect is due to interaction of dopant singlets with host triplets and polarons. ► Rate equations are developed to describe all aspects of the overshoot. ► A means to reduce this effect, and to achieve potentially higher quantum efficiency in ultrabright fluorescent OLEDs is to co-dope the emission layer with a fast phosphor molecule that acts as a triplet sink.