Tuning the AIE Activities and Emission Wavelengths of Tetraphenylethene-Containing Luminogens

Aggregation-induced emission (AIE) has attracted rapidly growing interest, owing to the high fundamental importance and diverse applications. The study of structure-property correlation of AIE luminogens is of high importance for the design and application of new AIE luminogens. In this contribution, we synthesized two pairs of tetraphenylethene-phenanthro[9,10-d] imidazole conjugates, and investigated the structure-property correlation of the luminogens. The optical properties, fluorescence lifetimes, electronic structures, electrochemical properties, and electroluminescence properties of the luminogens were comparatively studied. It was found that embedding benzo-2,1,3-thiadiazole moieties into the molecular backbones not only tuned the fluorescence feature of aggregation-enhanced emission to moderate aggregation-caused quenching, but also strongly red-shifted the fluorescence of luminogens from sky-blue to red. The underlying mechanism of this phenomenon was studied and discussed combined with theoretical calculation results. Undoped organic light-emitting diodes with varied electroluminescence colors and good performances are fabricated using these luminogens as light-emitting layers.