Ultra-Broadband Photoluminescent Carbon Dots Synthesized by Laser-Induced Thermal Shock

Carbon dots (CDs) emerge as a novel type of fluorescent materials with a good photostability, biocompatibility, and high quantum yield. They become a promising alternative to conventional fluorescent materials such as rare-earth phosphors and semiconductor quantum dots owing to their ease of synthesis and fabrication from ready-available compounds. Near-infrared (NIR) CDs are of high demand for in vivo studies owing to little photoinduced damage to surrounding tissues, deep penetration of radiation into tissue, and low autofluorescence. A laser-assisted synthesis approach is demonstrated, which allows NIR-emitting CDs to be obtained. By rapidly heating the precursors (4,4’-bis(diethylamino)benzophenone in sol–gel matrix) with femtosecond pulses, NIR emitting CDs can be obtained with the emission in the ranges of 800–1000 and 1100–1600 nm of the resulting CDs.