Intramolecular Through-Space Charge Transfer Based TADF-Active Multifunctional Emitters for High Efficiency Solution-Processed OLED

Thermally activated delayed fluorescence (TADF) has been explored actively in luminescent organic materials. Yet, realizing such TADF-active, multifunctional emitters with high emission efficiency still remains hugely challenging. In this context, a series of twist-conjugated organic molecules bearing diphenylsulfone and 9,9-dimethylacridine moieties are designed and prepared, and are found to show, in one molecule, TADF, room-temperature phosphorescence, triboluminescence, and aggregation-induced emission enhancement. In addition, remarkably high photoluminescence quantum efficiency, up to approximate to 100%, is achieved for these novel molecules. Single-crystal analysis and theoretical calculations reveal that the through-space charge transfer (TSCT) effect in these molecules is responsible for both the multifunctional emission and high emission efficiency. A maximum external quantum efficiency of 20.1% is achieved, which is among the highest recorded in a solution-processable device containing TSCT-based TADF materials. These results illustrate a new approach to achieving highly efficient TADF-active, multifunctional emitters.