Effect of Ligand Concentration, Dilution, and Excitation Wavelength on the Emission Properties of CdSe/CdS Core Shell Quantum Dots and Their Implication on Detection of Uranium

Abstract

Many applications of quantum dots (QDs); such as solar energy harvesting and toxic ion detection advice to understand the photoluminescence properties of QDs in water. However, this property can vary with concentration, purification and excitation wavelength which is seldom understood and can affect the above mentioned applications. The work carried out in this article demonstrates the effect and importance of these parameters on the photoluminescence properties of water dispersible CdSe/CdS core shell QDs. Three core shell QDs having the same core and shell thickness, but different number of ligands were synthesized. It was observed that the ligand concentration, excitation wavelength and concentration has a profound effect on the emission properties of QDs. The effect of above mentioned parameters on the detection of uranium by QDs was also discussed and it was shown that tuning these parameters can impact the detection limit drastically. A detection limit of 10 ppb was achieved by varying the experimental conditions which is much below than the limit prescribed by World Health Organization for uranium in drinking water suggesting the potential of these dots in sensing application and importance to tune different experimental conditions to achieve at a better detection limit.