The Effect of Plasmons of Silver Nanoparticles on the Luminescence of S,N-Doped Carbon Dots
Abstract
The plasmon effect of Ag nanoparticles on the generation and deactivation of singlet and triplet electron states was studied in solid films of S- and N-doped carbon dots. For this, carbon dots were synthesized with the sizes from 4 to 10 nm. The best emissivity was found for carbon dots based on the citric acid and L-cysteine at the ratio of 1:0.5. It is shown that synthesized carbon dots efficiently generate triplet-excited states. Their deactivation is carried out in two ways – through phosphorescence (at ~560 nm) and delayed fluorescence (at ~440 nm). At the same time, the effect of silver nanoparticles on the absorption and luminescence of carbon dot films was studied. It has been demonstrated for the first time that the presence of Ag nanoparticles leads to the growth in the intensity of long-lived luminescence of carbon dots. The intensity of fluorescence was increased by 1.6 times, and long-lived luminescence – by 2.7 times. The effect of the luminescence enhancement of carbon dots can be in demand in such applications as photodynamic therapy, bioimaging, anti-counterfeiting coatings and latent imaging, organic light-emitting diodes (OLEDs), sensors, etc.