Polymer Composite Materials Based on Carbon Dots

Carbon dots (C-dots) are promising nanomaterials with unique optical properties, including high photoluminescence, stability, and low toxicity compared to traditional luminophores. They can be used as luminophores in light-emitting diodes or as active layers in electroluminescent devices and have a long service life. However, their practical application is limited by their tendency to aggregate and concentration quenching in aqueous media. In this work, a method is proposed for stabilizing C-dots by incorporating them into polymer matrices—polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA), which makes it possible to obtain transparent, mechanically strong, and highly efficient luminescent composite materials. C-dots were synthesized by the hydrothermal method from o-phenylenediamine, which ensured a high quantum yield (25%) and luminescence in the blue region of the visible spectrum. It was established that the optimal concentration of C-dots in water is 0.02 wt %, but their introduction into polymer matrices made it possible to significantly increase the content of nanoparticles without loss of luminescent properties. The highest luminescence intensity was observed at a concentration of 1.6 wt % C-dots in both polymer matrices. Using fluorescence microscopy, the uniform distribution of carbon dots in the polymers was confirmed, and on the basis of spectrophotometric analysis it was shown that the composite films possess high transparency throughout the entire visible range. At the same time, the films demonstrated good photostability: after 6 h of UV irradiation, the decrease in intensity was 27% for PVA-based composites and 30% for PVP-based ones. The obtained results demonstrate that the resulting polymer composite materials based on C-dots possess promising characteristics for application as light-converting coatings and components of various optoelectronic devices for display and information transmission, including light-emitting diodes, organic displays, light converters, and others.