Enhancement of the Collective Optical Properties of Plasmonic Hybrid Carbon Dots via Localized Surface Plasmon

We report on the photophysical properties of the synthesized Plasmonic/Carbon dots (C-Dots/Plasmonic) nanohybrids prepared by the physical mixing of carbon dots with plasmonic nanoparticles such as gold and silver nanoparticles. Remarkable enhancements on the optical parameters such as absorptivity and fluorescence quantum yield, accompanied with the reduction in the rate of electron-hole recombination were observed for the hybrid nanostructure compared to pure carbon dots. This enhancement is due to enhancing the incident excitation field via localized surface Plasmon in the metallic part, which leads to increasing the exciton radiative recombination rate in the carbon dots, which is dependent on the spectral overlap in the absorption spectra. This plasmonic enhancement was more pronounced in the case of carbon dots - silver (C-Dots/Ag) nanohybrids than that of carbon dots - gold (C-Dots/Au) nanohybrids, due to low intrinsic loss and the degree of the overlap between the absorption spectra of silver nanoparticle and carbon dots. Furthermore, picosecond decay measurements show a decreased lifetime of carbon dots on the presence of plasmonic, due to the increased rates of radiative decay. The unique characteristics of the proposed Plasmonic/C-Dots can be used for application in single and multiple biological sensing or imaging.