Due to their exceptional properties such as low toxicity, stable photoluminescence, chemical stability and pronounced quantum confinement effect, GQDs are considered as a novel material for biological, opto-electronics, energy and environmental applications.
The origin of GQD fluorescence emission is a subject of debate, as it has been related to quantum confinement effects, defect states and functional groups[4][5] that might depend on the pH, when GQDs are dispersed in water.
[6] Their electronic structure depends sensitively on the crystallographic orientation of their edges, for example zigzag-edge GQDs with 7-8 nm diameter show a metallic behavior.
[10] Many authors claim, that GQDs are biocompatible and cause only low toxicity[2][11] as they are just composed of organic materials, which should lead to an advantage over semiconductor quantum dots.
They have possible applications in treatment of Alzheimer's disease, bioimaging,[28] photothermal therapy,[1][29] temperature sensing,[30] drug delivery,[31][32] LEDs lighter converters, photodetectors, OPV solar cells, and photoluminescent material, biosensors fabrication.