Synthesis of graphene quantum dot/metal-organic framework nanocomposites as yellow phosphors for white light-emitting diodes

A new luminescent composite material GQD@ZIF-8 was obtained by incorporating edge-sulfonated graphene quantum dots (GQDs) as an active fluorescent species into nanocrystals of the zeolitic imidazolate framework (ZIF-8) as both a stabilizer and a carrier by a simple, rapid, and eco-friendly approach. The as-synthesized GQD@ZIF-8 composite not only exhibits excellent fluorescence properties in aqueous solutions but can also emit bright fluorescence in the solid state due to the effective encapsulation by ZIF-8. The GQD@ZIF-8 nanocomposite was used as a novel yellow phosphor in the fabrication of white light-emitting diodes (WLEDs) based on a blue-light LED chip with a proximate CIE coordinate (0.33, 0.33) of highly pure white light and a relatively high color-rendering index.