Exploring the photophysical properties of CdS core and CdS@ZnS core-shell quantum dots for Hg²⁺-ion sensing and...

The creation of phosphor-converted materials for LEDs and sensing applications have become important due to growing demand for superior optical properties. Herein, we have synthesized N-acetyl-L-cysteine-capped CdS and CdS@ZnS quantum dots (QDs) via a simple aqueous synthesis method. The as-synthesized QDs show a long average PL lifetime, good stability under normal conditions, and an average particle size of less than 10 nm. Interestingly, the synthesized QDs show fluorescence-based Hg²⁺-ion detection, with a detection limit of 0.78 µM and 0.45 µM for the core and core-shell QDs, respectively. The detection process was thoroughly examined and attributed to the photoinduced electron transfer from QDs to mercury ions. With a recovery percentage of ∼90-118%, the effective application of synthesized QDs for mercury-ion detection has been established in real-sample analysis. Furthermore, the synthesized QDs can be used for white pc-LED application because of its better chromaticity coordinates of (0.31, 0.41) and (0.32, 0.42), a color rendering index (CRI) value of 71 and correlated color temperature (CCT) values of ∼6222 K and ∼5875 K for CdS and CdS@ZnS QDs, respectively. Thus, they may be employed as advanced materials for future low-cost LED-based devices.