Investigation of Heavy Atom Effect on Fluorescence of Carbon Dots: NCDs and S,N-CDs.

The present work is an attempt to investigate the heavy atom effect imparted by halide ions, especially iodide (I-) ions on the fluorescence behavior of carbon dots (CDs). Here two different types of CDs viz. nitrogen doped carbon dots (NCDs) from Citric Acid (CA) & Urea and Sulfur and nitrogen co-doped carbon dots (S,N-CDs) from CA & L-Cysteine were synthesized and the fluorescence of both CDs were quenched by heavy atom effect on adding potassium iodide (KI). The large difference in average lifetime was obtained in time-correlated single-photon counting (TCSPC) analysis suggests the dynamic quenching and heavy atom effect. Graphical abstract.