Photoluminescence of graphene quantum dots enhanced by microwave post-treatment

• The QYs of GQDs can be increased significantly by microwave post-treatment. Graphene quantum dots (GQDs) have a great potential in sensors and bioimaging for their lower toxicity, perfect water solubility and bright luminescence. However, considerable efforts still need to devote to enhance the photoluminescence quantum yields (PLQYs) of GQDs. At first, high PLQYs are guaranteed by confined synthesizing GQDs/layered double hydroxides (LDHs) with well-defined structure. Followed by a convenient microwave post-treatment, PLQYs of GQDs are further improved from 21.0% to 34.6%. After microwave post-treatment, the integrity of π-conjugated system has been enhanced and non-radiative processes also have been reduced inside GQDs, which both confirmed to be responsible for the improvement of PL properties. This work may point out a new direction for enhancing the PLQYs of GQDs. Moreover, owing to the stability and well PL performance of GQDs/LDHs, it has a great potential application in the outdoor anti-counterfeiting inks.