Description

Thermally activated delayed fluorescence (TADF) based on through‐space donor and acceptor interactions constitute a recent and promising approach to develop efficient TADF emitters. Novel TADF isomers using a dithia[3.3]‐paracyclophane building block as a versatile 3D platform to promote through‐space interactions are presented. Such a 3D platform allows to bring together the D and A units into close proximity and to probe the effect of their orientation, contact site and distance on their TADF emission properties. This study provides evidence that the dithia[3.3]paracyclophane core is a promising platform to control intramolecular through‐space interactions and obtain an efficient TADF emission with short reverse‐intersystem crossing (RISC) lifetimes. In addition, this study demonstrates that this design can tune the energy levels of the triplet states and leads to an upconversion from ³CT to ³LE that promotes faster and more efficient RISC to the ¹CT singlet state.