Facile one-step sonochemical synthesis of ultrafine and stable fluorescent C-dots.

This work describes a one-step synthesis of carbon dots (C-dots), which is carried out by sonication of polyethylene glycol (PEG-400) for 0.5-3h. The effect of the various experimental parameters, such as sonication time, amplitude and temperature on the size and the fluorescence of the C-dots was studied. It was found that the average diameter of the C-dots is between 2 and 9 nm, depending on the preparation conditions. The highest quantum yield of emission was ∼ 16%. These high fluorescence properties of the C-dots could be used for bioimaging and for solar cell applications.