Preparation of high-performance few-layer tungsten disulfide (WS2) quantum dots by regulating hydrodynamic cavitation parameters for application in white emission LEDs

Abstract

Tungsten disulfide quantum dots (WS₂ QDs) exhibit extensive application prospects in various fields such as light-emitting devices, photocatalysis, sensors and anti-counterfeiting due to their excellent optical and electrical properties. In this study, high-performance WS₂ QDs were successfully prepared by using the hydrodynamic cavitation (HC) technology, which is simple to operate, controllable in process, resource-conserving. In the HC system, the collapse of cavitation bubbles generates an extremely harsh environment with ultra-high temperature and pressure. Furthermore, the intense shock waves, high-speed jets, and turbulence induced in the solution by HC collectively act on the WS₂ powder in the fluid. These factors not only facilitate the continuous fragmentation of WS₂ powder into WS₂ QDs but also ensure the full dispersion of the WS₂ QDs in the solution. The WS₂ QDs featuring small particle size (1.50 nm), narrow particle size distribution range (0.86–2.40 nm) and few layers (2–4 layers) can be obtained by optimizing reaction conditions (HC cycle time and inlet pressure) and device parameters (number of holes and thickness of orifice plates). When the WS₂ QDs solutions were stored in low temperature (4 °C), light-avoiding and weakly alkaline (pH = 9.0) conditions, they exhibited good stability. Additionally, the as-prepared WS₂ QDs were applied to fabricate light-emitting diodes (LEDs), and the results showed that the fabricated LED can emit white light. Finally, it is hoped that this study can provide a novel idea for large-scale preparation of WS₂ QDs, which can be applied to fabricate white-light-emitting LEDs and other potential applications.