Carbon dots were synthesized using a solvothermal method with various carbon sources and synthesis temperatures. The particle size, surface morphology, and structural and luminescent characteristics was analyzed as functions of the synthesis temperatures. The transmission electron microscope images of the carbon dots showed that the surface morphology of the carbon dots was different for different carbon sources and synthesis temperatures. The Raman spectra of the carbon dots showed that depending on the synthesis conditions, the carbon dots could have an amorphous or a two-dimensional crystalline structure. Under 340-nm excitation, the carbon dots exhibited a dominant blue emission centered at 410 nm. Increasing the synthesis temperature raised the luminescent intensity of the carbon dots due to an increase the number of defect states during a synthesis process at a high temperature. A fluorescent ink for anti-counterfeiting applications was fabricated by using carbon dots and anti-counterfeiting patterns were printed with higher resolution and covertness. Considering these results, we conclude that carbon dots are promising fluorescent materials for was in anti-counterfeiting applications.

Keywords: Carbon dots, Photoluminescence, Anti-counterfeiting