Synthesis of MoS₂ Quantum Dots Uniformly Dispersed on Low Dimensional MoS₂ Nanosheets and Unravelling its Multiple Emissive States

Abstract

We demonstrate a simple and green route for the synthesis of MoS2 quantum dots (QDs) of size 1‐4 nm dispersed uniformly over the mono and bilayered, low dimensional MoS2 sheets, referred as MoS2 quantum dots dispersed over nanosheets (MoS2 QDNS). The synthesis was accomplished by the high temperature hydrothermal reaction of bulk MoS2 in aqueous NaOH. The MoS2 QDNS displays luminescence emission spanning a large portion of the UV and visible region of electromagnetic spectrum, envisaged to stem from both QDs and the nanosheets. A detailed photophysical characterization including time resolved fluorescence were carried out to unfold the origin of photoluminescence (PL) emission from this hybrid nanostructure. Our studies reveal that, blue and red portion of the emission are solely from QDs and the nanosheets, respectively. Whereas intermediate segment of the emission hail from the synergistic contribution of QDs and nanosheets. The MoS2 QDNS, manifests excellent stability, retained its characteristic morphology and PL even after several months. Finally, the excellent pH responsive PL emission of MoS2 QDNS makes them a promising candidate for biological and environmental applications.

Mixed Phase MoS2 Quantum Dots as Optical Limiters for Ultrafast Lasers

“…The lifetime component with the highest amplitude is associated with the bandgap emission, while the other lifetime component having a smaller contribution is associated with edge and defect states emission . Moreover, similar to previous observations, the longer lifetime can be associated with the small size of the quantum dots. It is also seen that as the probe wavelength is increased, the lifetimes become shorter because at a longer wavelength, the PL is likely from a larger dot.…”

Synthesis and characterisation of MoS2 quantum dots by liquid nitrogen quenching

“…A s and A r are the absorbance of the sample and reference, which are obtained from the absorption spectra [39]. The fluorescence quantum yield of the synthesised MoS 2 QDs is found to be 5.06%, which is higher than that of previously reported value for MoS 2 QDs [40].…”

Direct Patterning of Optoelectronic Nanostructures Using Encapsulated Layered Transition Metal Dichalcogenides

“…A variety of methods have been identified for realizing TMD nanostructures, including chemically synthesized dots, − sonicated and centrifuged flakes, − helium ion-beam patterning, , direct femtosecond laser writing, laser ablation, electron beam (e-beam) lithography, and gate-defined quantum dots . Some of these approaches, such as sonication and dot synthesis, can achieve very small TMD nanostructures with measurable confinement energies, but they typically lack controllable size, placement, and distribution.…”