Bright Blue-Light emitting cobalt doped CuS quantum dots: Photophysical studies and selective sensing application of ferric ion

Surface-functionalized quantum dots (QDs) have garnered significant attention in recent years for a variety of applications, including LEDs, photovoltaics, sensing, bioimaging and biomedical domains due to their distinct optical features such as strong photoluminescence behavior, high quantum yields etc. However, formation of nontoxic QDs is very challenging for the researchers because of their lower optical properties as compared to Cd based QDs. The phenomenon of doping in semiconductor QDs is an effective way to achieve high opto-electrical properties in the host QDs. We have presented a low temperature colloidal synthesis of CuS QDs using cobalt (Co²⁺) as a doping agent with an exceptional stability at room temperature for 30 days. The photoluminescence (PL) properties of Co²⁺-doped CuS QDs exhibit a deep-blue emission at 420 nm resulting in excellent optical property with an improvement of photoluminescence quantum yield. Due to remarkable CIE chromaticity coordinates, good CCT values, and high colour purity, the synthesized Co²⁺-doped CuS QDs could be used extensively in LEDs and prove to be useful as blue phosphors. The synthesized Co²⁺-doped CuS QDs also act as a fluorescence probe in the detection of ferric ion (Fe³⁺) with high sensitivity, good selectivity, a low limit of detection (LOD) and limit of quantification (LOQ), of (4.99 ± 0.12) μM and (16.67 ± 0.40) μM, respectively.