Investigation of the Possibility of Bulk Material Marking by Quantum Dots

This work is devoted to the search for methods of labeling powder materials. The labeling was performed with CdSe/CdS/ZnS quantum dots synthesized in an oleic acid medium. Cyanuric acid powder was selected as a bulk material model for the study. The choice of cyanuric acid as a model powder material was justified by its low toxicity, relative cheapness and accessibility, as well as insolubility in organic solvents used for the quantum dots synthesis. In addition, the criterion for choosing cyanuric acid was that its own luminescence spectrum was shifted relative to the spectra of the quantum dots selected for the study. The solubility of cyanuric acid in organic solvents used for the synthesis of quantum dots was evaluated; the flowability of the powder and the effect of exposure to solvents on it were analyzed. Samples of cyanuric acid powder marked with quantum dots with different luminescence peak positions and intensities were obtained. The luminescent properties of the obtained powders were investigated, the minimum amount of powder with quantum dots applied to the surface in the total composition sufficient for labeling was estimated, and the effect of applying quantum dots to the surface on the flowability of the powder was estimated. The possibility of marking bulk material with compositions of quantum dots with clearly defined monochromatic luminescence bands to create an invisible “fingerprint,” which is determined in laboratory conditions, is investigated.