Excited-state conformation capture by supramolecular chains towards triplet-involved organic emitters

Nowadays, the development of triplet-involved materials becomes a hot research topic in solid-state luminescence fields. However, the mechanism of triplet-involved emission still remains some mysteries to conquer. Here, we proposed a new concept of excited-state conformation capture for the constructions of different types of triplet-involved materials. Firstly, excited-state conformation could be trapped by supramolecular chains in crystal and form a new optimum excited-state structure which is different from that in solution or simple rigid environment, leading to bright thermally activated delayed fluorescence (TADF) emission. Based on excited-state conformation capture methodology, next, we obtained room-temperature phosphorescence (RTP) by introducing Br atoms for the enhancement of intersystem crossing. It could be concluded from experimental results that TADF may originate from aggregate effect while RTP may derive from monomers. Finally, heavy-atom free RTP and ultra RTP were achieved by eliminating aggregate effect. This work could not only extend the design methodology of triplet-involved materials but also set clear evidences for the mechanism of triplet-involved emissions.