Down-conversion monochromatic light-emitting diodes with the color determined by the active layer thickness and concentration of carbon dots

We report a series of monochromatic light-emitting diodes based on monodisperse carbon dots with an emission color ranging from blue to red, which is determined by the thickness of the down-conversion layers and the carbon dot doping concentration in the polymer matrix. We further demonstrate the potential of CDs for fabrication of relief graphical patterns with anti-counterfeiting security.