Carbon Quantum Dots with Solvent Dependent Aggregation and Fluorescence Emission Properties

Carbon Quantum Dots (CQDs) are a class of nanoparticles with increasing interest due to their unique chemical and optical properties, notably their prominent fluorescence and characteristic excitation dependent emission. While solvent induced changes in fluorescence are reported, we have observed a unique and uncharacteristically large shift in both excitation and emission wavelengths of 4-(methylthio)benzaldehyde derived CQDs dependent on the solvent and its dielectric constant. Furthermore, we observed a deviation of the characteristic excitation dependent emission normally seen in carbon quantum dots to a stable emission in water, which may be a result of a shift from CQD fluorescence to fluorescence of aggregated particles. This work aims to characterize the CQD system in different solvents and to relate these unique fluorescence properties to the physical alterations.