Recent Advances in the Synthesis, Optical Properties, and Applications of Fluorescent Silicon Carbide Quantum Dots

Earth-abundant, fluorescent silicon carbide (SiC) quantum dots (QDs) have recently attracted remarkable attention on account of their long-term chemical and optical stability and impressive biocompatibility. However, there has been a long-standing debate among researchers concerning whether radiative recombination in SiC QDs is governed by quantum confinement effects or by surface-related states. Herein, the underlying mechanism responsible for the photoluminescence observed in SiC QDs is elucidated. Significant progress made through the development of advanced strategies for synthesizing ultrasmall SiC QDs and modifying their surfaces with functional groups, conjugated molecules, and protective shells is discussed. Subsequently, the potential for engineered SiC QDs to be applied to a range of sectors, including energy (photocatalytic-based CO₂ reduction systems), electronics/optoelectronics (electroluminescent white light-emitting diodes, nonlinear optics, and quantum sensing), and biomedicine (cell imaging and biosensors), is reviewed. Finally, this review is summarized with some forward-looking challenges and prospects.