Fast Delayed Emission In New Pyridazine-Based Compounds

Three novel donor-acceptor molecules comprising the underexplored pyridazine (Pydz) acceptor moiety have been synthesized and their structural, electrochemical and photophysical properties thoroughly characterized. Combining Pydz with two phenoxazine donor units linked via a phenyl bridge in a meta configuration (dPXZMePydz) leads to high reverse intersystem crossing rate k(RISC) = 3.9 center dot 10(6) s(-1) and fast thermally activated delayed fluorescence (TADF) with dPXZMePydz as the emitter but does not occur for compounds bearing weaker donor units.