Seeking brightness from nature: Sustainable carbon dots-based AIEgens with tunable emission wavelength from natural rosin

Aggregation-induced emission luminogens (AIEgens) have many applications, including bioimaging, organic light-emitting diodes, sensing and anti-cancer therapy. Most AIEgens, however, suffer from unsustainable synthesis. Here, we have developed carbon dots-based AIEgens (CD-AIEgens), with adjustable fluorescence wavelength, that can be prepared from sustainable rosin in a one-step hydrothermal process. The fluorescence wavelength of solutions containing as-prepared CD-AIEgens can be adjusted between 430 nm and 582 nm by varying the concentration. The adjustable emissive wavelength is attributed to inherent FRET between the carbon cores and aggregates of tricyclic phenanthrene moieties on the surface of the CD-AIEgens. Making use of their adjustable fluorescence, we successfully used the CD-AIEgens as a two-switch-mode luminescence ink for encryption.