Tunable Double Phosphorescence Components From a Single Organic Molecule: Benzo[ <i>c</i> ][1,2,5]Thiadiazole Works as Both Electron Acceptor and Phosphorescence Emitting Center

ABSTRACT To date, reports of purely organic molecules exhibiting double phosphorescence emission are still rare, primarily due to the difficulty in simultaneously stabilizing multiple emissive triplet states within a single molecule. In this work, we report tunable double phosphorescence components from a single organic molecule NSBCz composed of a benzo[c][1,2,5]thiadiazole (NS) unit and a benzo[c]carbazole (BCz) moiety. The two phosphorescence units are connected via a carbon‐nitrogen single bond and NS works as both electron acceptor and phosphorescence emitting center. Specifically, NSBCz demonstrates matrix‐dependent color‐tunable room temperature phosphorescence in different polymer films such as PVA, PMMA, copolymerized MMA film owing to selective expression of double phosphorescence components. Loose matrix (PMMA) benefits red phosphorescence from T 1 as electron communication from BCz to NS occurs smoothly. Dense matrix (PVA and copolymerized MMA film) enables coexistence of green phosphorescence from T 2 and red phosphorescence from T 1 because electron communication between NS and BCz is greatly inhibited. To reveal halogen atom effect on double phosphorescence components, NSBCzF and NSBCzBr are synthesized. For both controls, the selective expression of double phosphorescence components are also shown and the lifetime and intensity of each phosphorescence component greatly depend on halogen atom.