Thermally Activated Delayed Phosphorescence and Interchromophore Exciton Coupling in a Platinum-Based Organometallic Emitter

The comprehension of triplet exciton mechanisms in organic–inorganic semiconductors has a significant impact on emerging optoelectronic and biosensing technologies. The capability to mutually integrate the photophysical properties of conjugated organic semiconductor with those of well-characterized heavy metals is therefore of utmost importance. Due to heavy-atom effect, the platinum-based triplet emitter, PPtTPtT, achieves highly efficient phosphorescence. Here, it is first demonstrated that π-conjugated PPtTPtT organometallics in electrochemiluminescence (ECL) devices exhibit precisely dual and blueshifted phosphorescence simultaneously induced by thermally activated delayed phosphorescence (TADP) and interchromophore exciton interaction in H-aggregates. Utilizing a combination of photophysical and electrochemical techniques, the distinctive ECL process involving energy sufficient singlet route (S-route), intersystem crossing, as well as triplet relaxation, hereafter called SIT-route, is reported for the first time. The hybrid TADP materials designed with donor–acceptor–donor system enable potential applications, including but not limited to organic light-emitting diodes, light-emitting electrochemical cells, imaging devices, and other bio-related detections.