Photoluminescence enhancement of carbon quantum dots via the synergistic effect of thiol-ene cross-linking and gold nanoparticles

The co-doping of the CQDs and gold nanoparticles (Au NPs) in the non-stoichiometric thiol-ene (OSTE) polymer was prepared through “click” chemistry reaction. It is interesting to find that the excitation-independent behavior of the CQDs is converted into an excitation-dependent characteristic after polymerization with the OSTE, likely due to changes in the CQDs’ electronic structure. Meanwhile, the PL intensity is also enhanced, being approximately 3 times stronger than that of CQDs in toluene solution. In addition, the PL intensity of the Au-CQDs/OSTE composite reaches its maximum as the concentration of Au NPs is 2.5×10^-6 M, which is about 1.87-fold and 1.35-fold stronger than that of CQDs in toluene solution and CQDs/OSTE composite, respectively. We demonstrate that the cross-linking effect of the OSTE polymer, along with the localized surface plasmon resonance (LSPR) effect of the Au NPs, are responsible for the increased PL intensity of the CQDs.