Carbon Dots

Fluorescent carbon dots (CDs) are a new class of carbon nanomaterials and have demonstrated excellent optical properties, good biocompatibility, great aqueous solubility, low cost, simple synthesis, etc. Since their discovery, various synthesis methods using different precursors have been developed, and are mainly classified as top-down and bottom-up approaches. For the mechanistic origin of CDs photoluminescence, three mechanisms have been proposed such as quantum confinement effect, surface state and molecule state.

Carbon dots (CDs, also called as carbon quantum dots, or carbon nanoparticles (CNPs)), which are one kind of newly discovered fluorescent nanomaterials, have become increasingly popular in the past decade due to their unique optical properties, good biocompatibility, low toxicity, great aqueous stability, facile synthesis, etc.

Carbon dots are generally quasi-spherical nanoparticles comprising amorphous to nanocrystalline and always consist of sp2/sp3 carbon, oxygen/nitrogen based groups, and post-modified chemical groups. To possess fluorescent properties, the size and surface chemical groups of carbon dots should be carefully modulated. Especially, the emission of CDs could be adjusted by controlling the condensation reaction, chemical manipulations, or most commonly by doping in of other elements.

The structures and components of CQDs determine their diverse properties. Many carboxyl moieties on the CQD surface impart excellent solubility in water and biocompatibility. CQDs are also suitable for chemical modification and surface passivation with various organic, polymeric, inorganic or biological materials. By surface passivation, the fluorescence properties as well as physical properties of CQDs are enhanced.

CQDs possess the potential in serving as materials for dye-sensitized solar cells, organic solar cells, supercapacitors, and light emitting devices. CQDs can be used as photo sensitizer in dye-sensitized solar cells and the photoelectric conversion efficiency is significantly enhanced. CQD incorporated hybrid silica based sol can be used as transparent Fluorescent paint