Highly emitting colloidal MoS2 quantum dots for optoelectronic applications

Abstract

Transition metal dichalcogenides (TMDs) are recognized as low toxicity materials with excellent physical, electrical, and optical properties. Molybdenum disulphide (MoS₂) is a prototype material in the family of 2D TMDs. Extensive exploration of the material has been done for the past decade. Owing to its peculiar optical and electronic properties such as high current carrying capacity, large carrier mobility, quantum confinement, and edge effects, it is a suitable candidate for optoelectronic and photonic applications. Although extensive exploration of 2D MoS₂ has taken place, not much work has been done on its 0D counterparts i.e., MoS₂-Quantum Dots (QDs). It is expected that MoS₂ QDs will be highly luminescent as compared to its 2D structures due to higher levels of confinement in QDs. We report, excellent emitting MoS₂ quantum dots (QDs) fabricated by a colloidal route. Optimization of the fabrication process was done to obtain the optimal temperature, precursor concentration, and ligand concentrations for high-quality QD precipitation. By careful control of the synthesis conditions, colloidally synthesized MoS₂ quantum dots emitted blue color under UV illumination. To further investigate the quality of the QDs, their absorption and emission spectra were studied. The absorption edge is highly blue shifted to around 303 nm as compared to 600 nm in bulk, showing strong quantum confinement effects. The QDs show emission spectra centered around 401 nm at incident excitation wavelength of 360 nm. It is observed that the MoS₂ QDs were highly stable which could lead to application in optoelectronics.