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

Abstract 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.